Quinoxaline derivatives as GPR6 modulators

ABSTRACT

The present invention provides compounds of Formula (I): 
                         
that are GPR6 modulators and are therefore useful for the treatment of diseases treatable by modulation of GPR6, in particular treating Parkinson disease, levodopa induced dyskinesias, Huntington&#39;s disease, other dyskinesias, akinesias, and motor disorders involving dysfunction of the striatum, schizophrenia and drug addiction. Also provided are pharmaceutical compositions containing such compounds and processes for preparing such compounds.

FIELD OF INVENTION

The present invention provides compounds that are G-protein-coupled receptor 6 (hereinafter referred to as GPR6) modulators and are therefore useful for the treatment of diseases treatable by modulation of GPR6, in particular treating Parkinson disease, levodopa induced dyskinesias, Huntington's disease, other dyskinesias, akinesias, and motor disorders involving dysfunction of the striatum, schizophrenia and drug addiction. Also provided are pharmaceutical compositions containing such compounds and processes for preparing such compounds.

BACKGROUND

Parkinson disease (PD) is a degenerative disorder of the central nervous system. The motor symptoms of Parkinson's disease result from the death of dopamine-generating cells in the substantia nigra, a region of the midbrain. Degeneration of the nigrostriatal pathway causes reduction in the striatal concentration of dopamine Dopamine is a neurotransmitter or chemical messenger in the body which affects brain processes controlling movement, balance, walking, emotional response, and ability to experience pleasure and pain. The major striatal targets of dopaminergic innervation reside in the medium spiny neurons (MSNs) of the striatopallidal (indirect) and striatonigral (direct) output pathways. The MSNs of the direct output pathway express D1 dopamine receptors whereas those in the indirect pathway express D2 receptors. Currently, there is no cure for Parkinson's disease, but drugs can relieve at least some of the symptoms. Modern treatments are effective at managing the early motor symptoms of the disease, mainly through the use of levodopa. About 75% of Parkinson's disease patients are treated with levodopa, a prodrug for dopamine discovered over 50 years ago (Dopamine Replacement Therapy).

Levodopa has common serious side effects including induced dyskinesia (LID), impulsive control disorders (ICD), psychotic symptoms and sleep disturbances. LID is progressive (90% of PD patients develop LID within 10 yrs). Accordingly there is a need for new treatments that are effective in treating PD. The present invention can fulfill this and related needs.

SUMMARY

Irreversible adaptations occur in D1 receptor signaling in MSNs in rodent models of LID including reduced desensitization leading of hypersensitivity in the direct pathway. Genetic inactivation of D1 but not D2 receptors abolishes LID in mice. However blockade of D1 receptor signaling does not affect the antiparkinsonian efficacy of L-DOPA. cAMP pathways modulated by D1/D2 dopamine receptors in MSN have been implicated in LID. Dopamine D2 receptors in MSN are Gi coupled, i.e., an agonist of D2 decreases the level of intracellular cAMP.

The GPR6 receptor exhibits high expression in the central nervous system (CNS) with minimal expression in peripheral tissues. GPR6 is highly selectively enriched in D2 receptor expressing MSNs in the striatum. The striatum plays a central role in modulating important behaviors including movement, reward, and motivational processes. GPR6 is GPCR that exhibits receptor signaling via the Gs pathway. Thus, GPR6 agonist activity results in an increase in intracellular cAMP levels whereas antagonists or inverse agonists cause a decrease in cAMP levels. GPR6 activity is therefore functionally opposed to D2 receptor signaling. Therefore, antagonism or inverse agonism of Gs coupled GPR6 should decrease cAMP in MSNs—a functional alternative to dopamine mediated activation of D2 receptors. As such, compounds that modulate the activity of GPR6 have utility in a variety of neurological and psychiatric disorders, for example movement disorders including Parkinson's disease, levodopa induced dyskinesias, and Huntington's disease either alone or in combination with other agents are approved for the treatment of Parkinson's disease including L-DOPA, dopaminergic agonists, MAO B inhibitors, DOPA decarboxylase inhibitors and COMT inhibitors. Other potential disease indications that could be treated by modulation of GPR6 include non-levodopa induced dyskinesias, akinesias, and motor disorders involving dysfunction of the striatum drug addiction and eating disorders, cognitive disorders, schizophrenia, bipolar disorders, and depression.

Accordingly, in a first aspect, provided is a compound of Formula (I):

wherein:

R¹ is a heterocycloamino ring substituted with R^(a), R^(b), and R^(c) wherein:

-   -   R^(a) is —Z—Ar where Z is C₁₋₆ alkylene, C₁₋₆ haloalkylene, —O—,         —C(O)—, —NH—, or —S(O)n- wherein n is 0, 1, or 2; and Ar is         C₃₋₁₀ cycloalkyl, C₃₋₇ heterocycloalkyl, C₃₋₇         heterocycloalkenyl, C₆₋₁₀ aryl, or C₁₋₉ heteroaryl wherein C₃₋₁₀         cycloalkyl, C₃₋₇ heterocycloalkenyl, C₃₋₇ heterocycloalkyl,         C₆₋₁₀ aryl, and C₁₋₉ heteroaryl are optionally substituted with         1 to 3 substituents independently selected from C₁₋₆ alkyl,         halo, hydroxy, oxo, C₁₋₆ alkoxy, C₁₋₆ thioalkoxy, C₁₋₆         haloalkyl, C₁₋₆ hydroxyalkyl, C₁₋₆ haloalkoxy, C₁₋₆         alkylcarbonyl, C₁₋₆ alkylsulphonyl, cyano, C₂₋₁₂ alkoxyalkyloxy,         C₁₋₉ amide, or C₁₋₆ hydroxyalkyloxy; and     -   R^(b) and R^(c) are independently hydrogen, C₁₋₆ alkyl, hydroxy,         or halo;

R² is —OR^(e) or —NR^(d)R^(e) wherein R^(d) is hydrogen or C₁₋₆ alkyl and R^(e) is C₁₋₆ alkyl, C₁₋₆ haloalkyl, C₁₋₆ hydroxyalkyl, C₂₋₁₂ alkoxyalkyl, C₁₋₁₂ aminoalkyl, C₃₋₁₀ cycloalkyl, C₄₋₁₆ cycloalkylalkyl, C₆₋₁₀ aryl, C₁₋₉ heteroaryl, C₃₋₇ heterocyclyl, or C₃₋₇ heterocycloalkenyl wherein C₆₋₁₀ aryl, C₁₋₉ heteroaryl, C₃₋₇ heterocyclyl, and C₃₋₇ heterocycloalkenyl are optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, oxo, C₁₋₆ alkoxy, C₁₋₆ haloalkyl or C₁₋₆ haloalkoxy, or cyano;

all X¹-X⁴ are carbon or one or two of X¹-X⁴ are N and the rest of X¹-X⁴ are carbon;

R³, R⁴, R⁵, and R⁶ are independently absent, hydrogen, C₁₋₆ alkyl, halo, hydroxy, C₁₋₆ alkoxy, C₁₋₆ alkoxycarbonyl, C₁₋₆ haloalkyl, C₁₋₆ haloalkoxy, C₁₋₉ amide, C₃₋₇ heterocyclyl, C₁₋₈ alkylamino, or cyano;

or a pharmaceutically acceptable salt thereof.

In a second aspect, provided is a pharmaceutical composition comprising a compound of Formula (I) (or embodiments thereof disclosed herein) or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable excipient.

In a third aspect, provided is a method of treating a disease treatable by administration of an antagonist and/or inverse agonist of GPR6 which method comprises administrating to the patient in need thereof a therapeutically effective amount of a compound of Formula (I) (or embodiments thereof disclosed herein) or a pharmaceutically acceptable salt thereof.

The method of third aspect wherein the disease is Parkinson disease, levodopa induced dyskinesia, non-levodopa induced dyskinesias, akinesias, motor disorders involving dysfunction of the striatum, drug addiction, eating disorders, cognitive disorders, schizophrenia, bipolar disorders, or depression. The method of third aspect wherein the compound of Formula (I) is administered in combination with an antipsychotic drug. The method of third aspect wherein the compound of Formula (I) is administered in combination with a dopamine agonist (e.g., Levodopa).

In a fourth aspect, provided is a compound of Formula (I) (or any embodiments thereof) or a pharmaceutically acceptable salt thereof for use as medicament. In one aspect of the fourth aspect, provided is the use of a compound of Formula (I) (or any embodiments thereof) or the pharmaceutical salts thereof for the treatment of a disease treatable by administration of an antagonist and/or inverse agonist of GPR6 such as Parkinson disease, levodopa induced dyskinesia, non-levodopa induced dyskinesias, akinesias, motor disorders involving dysfunction of the striatum, drug addiction, eating disorders, cognitive disorders, schizophrenia, bipolar disorders, or depression. Also, one aspect of the fourth aspect, provided is the use of a compound of Formula (I) (or any embodiments thereof) or the pharmaceutical salts thereof in combination with an antipsychotic drug. Also, one aspect of the fourth aspect, provided is the use of a compound of Formula (I) (or any embodiments thereof) or the pharmaceutical salts thereof in combination with a dopamine agonist (e.g., Levodopa).

DETAILED DESCRIPTION Definitions

Unless otherwise stated, the following terms used in the specification and claims are defined for the purposes of this Application and have the following meaning:

“C₁₋₆ alkyl” means a linear saturated monovalent hydrocarbon radical of one to six carbon atoms or a branched saturated monovalent hydrocarbon radical of three to six carbon atoms, e.g., methyl, ethyl, propyl, 2-propyl, butyl (including all isomeric forms), pentyl (including all isomeric forms), and the like.

“C₁₋₄ alkyl” means a linear saturated monovalent hydrocarbon radical of one to four carbon atoms or a branched saturated monovalent hydrocarbon radical of three to four carbon atoms.

“C₁₋₈ alkylamino” means a —NR′R″ where R′ is hydrogen or C₁₋₄ alkyl and R″ is C₁₋₄ alkyl.

“C₁₋₆ alkylene” means a linear saturated divalent hydrocarbon radical of one to six carbon atoms or a branched saturated divalent hydrocarbon radical of two to six carbon atoms unless otherwise stated e.g., methylene, ethylene, propylene, 1-methylpropylene, 2-methylpropylene, butylene, pentylene, and the like.

“C₁₋₆ alkylsulfonyl” means a —SO₂R radical where R is C₁₋₆ alkyl as defined above, e.g., methylsulfonyl, ethylsulfonyl, and the like.

“C₁₋₉ amide” refers to a —C(O)NRR′ group in which R is selected from the group consisting of hydrogen and C₁₋₄ alkyl, and R′ is selected from the group consisting of hydrogen, C₁₋₄ alkyl, or R and R′ together with the nitrogen to which they are attached form a 4 to 8 membered, saturated, ring optionally having an additional ring heteroatom selected from the group N, O, and S, in particular, an azetinyl, pyrrolidinyl, piperidinyl, piperazinyl, 4-methylpiperazin-1-yl, or morpholinlyl ring.

“C₁₋₁₂ aminoalkyl” means a linear monovalent hydrocarbon radical of one to six carbon atoms or a branched monovalent hydrocarbon radical of three to six carbons substituted with at least one, preferably one or two, —NRR′ where R is hydrogen, C₁₋₆ alkyl, or —C(O)R″ where R″ is C₁₋₆ alkyl, each as defined above, and R′ is selected from hydrogen, C₁₋₆ alkyl, C₁₋₆ hydroxyalkyl, or C₂₋₁₂ alkoxyalkyl, each as defined herein, e.g., aminomethyl, methylaminoethyl, 2-ethylamino-2-methylethyl, 1,3-diaminopropyl, dimethylaminomethyl, diethylaminoethyl, acetylaminopropyl, and the like.

“C₁₋₆ alkoxy” means a —OR radical where R is C₁₋₆ alkyl as defined above, e.g., methoxy, ethoxy, propoxy, or 2-propoxy, n-, iso-, or tert-butoxy, and the like.

“C₂₋₁₂ alkoxyalkyl” means C₁₋₆ alkyl radical as defined above that is substituted with one or two C₁₋₆ alkoxy group as defined above, e.g., methoxymethyl, ethoxymethyl, 2-methoxyethyl, and the like.

“C₂₋₁₂ alkoxyalkyloxy” means —OR radical where R is C₂₋₁₂ alkoxyalkyl as defined above, e.g., methoxymethyloxy, 2-methoxyethyloxy, ethoxymethyloxy, and the like.

“C₁₋₆ alkylcarbonyl” means a —C(O)R radical where R is C₁₋₆ alkyl as defined above, e.g., methylcarbonyl, ethylcarbonyl, and the like.

“C₁₋₆ alkoxycarbonyl” means a —C(O)OR radical where R is C₁₋₆ alkyl as defined above, e.g., methoxycarbonyl, ethoxycarbonyl, and the like.

“C₆₋₁₀ aryl” means a monovalent monocyclic or bicyclic aromatic hydrocarbon radical of 6 to 10 ring atoms e.g., phenyl or naphthyl.

“C₃₋₁₀ cycloalkyl” means a cyclic saturated monovalent hydrocarbon radical of three to ten carbon atoms, e.g., cyclopropyl, cyclobutyl, cyclopentyl, or cyclohexyl, and the like.

“C₄₋₁₆ cycloalkylalkyl” means -(alkylene)-R where R is C₃₋₁₀ cycloalkyl as defined above, e.g., cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl, or cyclohexylmethyl, and the like.

“Carbonyl” means —C═(O) group.

“Halo” means fluoro, chloro, bromo, or iodo, preferably fluoro or chloro.

“C₁₋₆ haloalkyl” means C₁₋₆ alkyl radical as defined above, which is substituted with one or more halogen atoms, preferably one to five halogen atoms, preferably fluorine or chlorine, including those substituted with different halogens, e.g., —CH₂Cl, —CF₃, —CHF₂, —CH₂CF₃,

—CF₂CF₃, and the like. When the C₁₋₆ alkyl is substituted with only fluoro, it is referred to in this Application as C₁₋₆ fluoroalkyl.

“C₁₋₆ haloalkylene” means C₁₋₆ alkylene as defined above wherein one to three hydrogen atoms have been replaced by halo, preferably fluoro. e.g., fluoromethylene, difluoromethylene, 1, 2, or 3-fluoroethylene, —CH(CHF₂)—, —CH(CF₃)—, and the like.

“C₁₋₆ haloalkoxy” means a —OR radical where R is C₁₋₆ haloalkyl as defined above e.g., —OCF₃, —OCHF₂, and the like. When R is C₁₋₆ haloalkyl where the C₁₋₆ alkyl is substituted with only fluoro, it is referred to in this Application as fluoroalkoxy.

“C₁₋₆ hydroxyalkyl” means a linear monovalent hydrocarbon radical of one to six carbon atoms or a branched monovalent hydrocarbon radical of three to six carbons substituted with one or two hydroxy groups, provided that if two hydroxy groups are present they are not both on the same carbon atom. Representative examples include, but are not limited to, hydroxymethyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 1-(hydroxymethyl)-2-methylpropyl, 2-hydroxybutyl, 3-hydroxybutyl, 4-hydroxybutyl, 2,3-dihydroxypropyl, 1-(hydroxymethyl)-2-hydroxyethyl, 2,3-dihydroxybutyl, 3,4-dihydroxybutyl and 2-(hydroxymethyl)-3-hydroxypropyl, preferably 2-hydroxyethyl, 2,3-dihydroxypropyl, and 1-(hydroxymethyl)-2-hydroxyethyl.

“C₁₋₆ hydroxyalkoxy” or “C₁₋₆ hydroxyalkyloxy” means a —OR radical where R is hydroxyalkyl as defined above.

“C₃₋₇ heterocycloalkyl” or “C₃₋₇ heterocyclyl” means a saturated monovalent monocyclic group of 4 to 8 ring atoms in which one or two ring atoms are heteroatom selected from N, O, or S(O)n, where n is an integer from 0 to 2, the remaining ring atoms being C, unless stated otherwise. More specifically the term C₃₋₇ heterocyclyl includes, but is not limited to, pyrrolidinyl, piperidinyl, homopiperidinyl, morpholinyl, piperazinyl, tetrahydropyranyl, thiomorpholinyl, and the like.

The term “heterocyclamino” means a saturated monocyclic group of 4 to 8 ring atoms in which one or two ring atoms are heteroatom selected from N, O, or S(O)n where n is an integer from 0 to 2, provided that at least one ring member is N. More specifically the term heterocycloamino includes, but is not limited to, azetidinyl, pyrrolidinyl, piperidinyl, homopiperidinyl, morpholinyl, thiomorpholinyl, piperazinyl, homopiperazinyl, and the like.

“C₃₋₇ heterocycloalkenyl” or “C₃₋₇ heterocyclylalkenyl” means a nonaromatic, unsaturated monovalent monocyclic group of 4 to 8 ring atoms in which one or two ring atoms are heteroatom selected from N, O, or S(O)n, where n is an integer from 0 to 2, the remaining ring atoms being C. Additionally, one or two ring carbon atoms in the heterocyclalkenyl ring can optionally be replaced by a —C(O)— group. More specifically the term heterocycloalkenyl includes, but is not limited to, dihydropiperidinyl, and the like.

“C₁₋₉ heteroaryl” means a monovalent monocyclic or bicyclic fully unsaturated radical of 5 to 10 ring atoms where one or more, preferably one, two, or three, ring atoms are heteroatom selected from N, O, or S, the remaining ring atoms being carbon, unless stated otherwise. Representative examples include, but are not limited to, furyl, thienyl, pyrrolyl, imidazolyl, isothiazolyl, isoxazolyl, oxadiazolyl, oxazolyl, thiazolyl, thiadiazolyl, triazolyl, tetrazolyl, pyrazinyl, pyrazolyl, pyridazinyl, pyridyl, pyrimidyl, azepinyl, diazepinyl, benzazepinyl, benzodiazepinyl, benzofuryl, benzothienyl, indolyl, isoindolyl, benzimidazolyl, benzisothiazolyl, benzisoxazolyl, benzoxadiazolyl, benzoxazolyl, benzopyrazinyl, benzopyrazolyl, imidazopyridyl, pyrazolopyridyl, pyrrolopyridyl, quinazolyl, thienopyridyl, imidazopyridyl, quinolyl, isoquinolyl benzothiazolyl, and the like.

“C₁₋₆ thioalkoxy” means a —SR radical where R is C₁₋₆ alkyl as defined above, e.g., thiomethoxy, thioethoxy, and the like.

“GPR6 modulators” as used herein means that the compounds of the invention are antagonists i.e., block the action of a GPR6 agonist by competitive binding to the GPR6 receptor or are inverse agonists of GPR6 i.e., bind to the GPR6 receptor and induces a pharmacological response opposite to its agonist thereby reducing its baseline intracellular activity. A GPR6 modulator may possess both antagonist and inverse agonist activity within the same compound.

The present invention also includes the prodrugs of compounds of Formula (I). The term prodrug is intended to represent covalently bonded carriers, which are capable of releasing the active ingredient of Formula (I) when the prodrug is administered to a mammalian subject. Release of the active ingredient occurs in vivo. Prodrugs can be prepared by techniques known to one skilled in the art. These techniques generally modify appropriate functional groups in a given compound. These modified functional groups however regenerate original functional groups in vivo or by routine manipulation. Prodrugs of compounds of Formula (I) include compounds wherein a hydroxy, amino, carboxylic, or a similar group is modified. Examples of prodrugs include, but are not limited to esters (e.g., acetate, formate, and benzoate derivatives), carbamates (e.g., N,N-dimethylaminocarbonyl) of hydroxy or amino functional groups in compounds of Formula (I)), amides (e.g., trifluoroacetylamino, acetylamino, and the like), and the like. Prodrugs of compounds of Formula (I) are also within the scope of this invention.

The present invention also includes protected derivatives of compounds of Formula (I). For example, when compounds of Formula (I) contain groups such as hydroxy, carboxy, thiol or any group containing a nitrogen atom(s), these groups can be protected with a suitable protecting groups. A comprehensive list of suitable protective groups can be found in T. W. Greene, Protective Groups in Organic Synthesis, John Wiley & Sons, Inc. (1999), the disclosure of which is incorporated herein by reference in its entirety. The protected derivatives of compounds of Formula (I) can be prepared by methods well known in the art.

A “pharmaceutically acceptable salt” of a compound means a salt that is pharmaceutically acceptable and that possesses the desired pharmacological activity of the parent compound. Such salts include: acid addition salts, formed with inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and the like; or formed with organic acids such as formic acid, acetic acid, propionic acid, hexanoic acid, cyclopentanepropionic acid, glycolic acid, pyruvic acid, lactic acid, malonic acid, succinic acid, malic acid, maleic acid, fumaric acid, tartaric acid, citric acid, benzoic acid, 3-(4-hydroxybenzoyl)benzoic acid, cinnamic acid, mandelic acid, methanesulfonic acid, ethanesulfonic acid, 1,2-ethanedisulfonic acid, 2-hydroxyethanesulfonic acid, benzenesulfonic acid, 4-chlorobenzenesulfonic acid, 2-naphthalenesulfonic acid, 4-toluenesulfonic acid, camphorsulfonic acid, glucoheptonic acid, 4,4′-methylenebis-(3-hydroxy-2-ene-1-carboxylic acid), 3-phenylpropionic acid, trimethylacetic acid, tertiary butylacetic acid, lauryl sulfuric acid, gluconic acid, glutamic acid, hydroxynaphthoic acid, salicylic acid, stearic acid, muconic acid, and the like; or salts formed when an acidic proton present in the parent compound either is replaced by a metal ion, e.g., an alkali metal ion, an alkaline earth ion, or an aluminum ion; or coordinates with an organic base such as ethanolamine, diethanolamine, triethanolamine, tromethamine, N-methylglucamine, and the like. It is understood that the pharmaceutically acceptable salts are non-toxic. Additional information on suitable pharmaceutically acceptable salts can be found in Remington's Pharmaceutical Sciences, 17th ed., Mack Publishing Company, Easton, Pa., 1985, which is incorporated herein by reference.

The compounds of the present invention may have asymmetric centers. Compounds of the present invention containing an asymmetrically substituted atom may be isolated in optically active or racemic forms. It is well known in the art how to prepare optically active forms, such as by resolution of materials. All chiral, diastereomeric, meso, racemic forms are within the scope of this invention, unless the specific stereochemistry or isomeric form is specifically indicated.

Additionally, as used herein the term C₁₋₆ alkyl and terms derived therefrom includes all the possible isomeric forms of said C₁₋₆ alkyl group. Furthermore, the cyclic groups such as C₆₋₁₀ aryl, C₁₋₉ heteroaryl, C₃₋₆ heterocycloalkyl include all the positional isomers. Furthermore, all polymorphic forms and hydrates of a compound of Formula (I) are within the scope of this invention.

The terms “compound” and “a compound of the invention” and “compound of the present invention” and the like, and their plural expressions include the embodiment of Formula (I) and the other more particular embodiments encompassed by Formula (I) described herein and exemplified compounds described herein and a pharmaceutically acceptable salt of each of these embodiments. All references to compounds, include all isotopes of the atoms contained therein, including isotopically-labeled compounds.

The compounds of the present invention may exist as tautomers. All tautomeric forms the compounds of the invention are contemplated to be within the scope of the present invention.

“Optional” or “optionally” means that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances in which it does not. For example, “C₃₋₆ heterocycloalkyl group optionally substituted with an C₁₋₆ alkyl group” means that the alkyl may but need not be present, and the description includes situations where the heterocycloalkyl group is substituted with an alkyl group and situations where the heterocycloalkyl group is not substituted with alkyl.

The terms “pharmaceutically acceptable carrier” or “pharmaceutically acceptable excipient” mean a carrier or an excipient that is useful in preparing a pharmaceutical composition that is generally safe, non-toxic in the amounts used, and neither biologically nor otherwise undesirable, and includes a carrier or an excipient that is acceptable for veterinary use as well as human pharmaceutical use. “A pharmaceutically acceptable carrier/excipient” as used in the specification and claims includes both one and more than one such excipient. Pharmaceutically acceptable excipients are well known in the art, such as those in Remington's Pharmaceutical Sciences, 17th ed., Mack Publishing Company, Easton, Pa., 1985.

The terms “condition,” “disorder,” and “disease” relate to any unhealthy or abnormal state.

“Treat,” “treating,” or “treatment” of a disease includes:

(1) preventing the disease, i.e. causing the clinical symptoms of the disease not to develop in a mammal that may be exposed to or predisposed to the disease but does not yet experience or display symptoms of the disease;

(2) inhibiting the disease, i.e., arresting, controlling, slowing, stopping, or reducing the development of the disease or its clinical symptoms; or

(3) relieving the disease, i.e., causing regression of the disease or its clinical symptoms or improvement of the disease or its clinical symptoms

The terms “treat,” “treating,” and “treatment,” do not necessarily indicate a total elimination of any or all symptoms or a cure of the disease.

As used herein the terms “patient” and “subject” includes humans and non-human animals, for example, mammals, such as mice, rats, guinea pigs, dogs, cats, rabbits, cows, horses, sheep, goats, and pigs. The term also includes birds, fish, reptiles, amphibians, and the like. It is understood that a more particular patient is a human. Also, more particular patients and subjects are non-human mammals, such as mice, rats, and dogs.

A “therapeutically effective amount” means the amount of a compound of Formula (I) that, when administered to a mammal for treating a disease, is sufficient to effect such treatment for the disease. The “therapeutically effective amount” will vary depending on the compound, the disease and its severity and the age, weight, etc., of the mammal to be treated. A “therapeutically effective amount” means the amount of a compound of Formula (I) or a pharmaceutically acceptable salt thereof that, when administered in single or multiple doses, to a mammal for treating a disease, is sufficient to effect such treatment for the disease. The “therapeutically effective amount” will vary depending on the compound, the disease and its severity and the age, weight, etc., of the mammal to be treated, the degree of or involvement or the severity of the condition, disorder, or disease, the response of the individual patient; the particular compound administered; the mode of administration; the bioavailability characteristics of the preparation administered; the dose regimen selected; the use of concomitant medication; and other relevant circumstances.

The term “disease treatable by administration of an antagonist and/or inverse agonist of GPR6” includes Parkinson Disease, levodopa induced dyskinesia, non-levodopa induced dyskinesias, akinesias, motor disorders involving dysfunction of the striatum, drug addiction, eating disorders, cognitive disorders, schizophrenia, bipolar disorders, or depression.

Representative compounds of Formula (I) having the structure where R^(b) and R^(c) are hydrogen and R* represents R³, R⁴, R⁵, and R⁶ and when other than hydrogen are identified at the positions indicated in Table 1 below are:

Compound Table 1 Cpd X Z Ar R^(e) R* Salt MSCalc MSObs

 1 N CH₂ 3-methylphenyl cyclopropyl TFA 373.494 374.3  4 N C(O) 3-CF₃phenyl cyclopropyl TFA 441.4489 442.3  5 N CH₂ 3-chlorophenyl cyclopropyl TFA 393.9124 394.2  6 N C(O) 4- cyclopropyl TFA 451.5413 452.2 methylsulfonylphenyl  7 N C(O) 2,5-dichlorophenyl cyclopropyl TFA 442.341 442.2  8 N C(O) 3,4-dichlorophenyl cyclopropyl TFA 442.341 442.2  9 N C(O) 3-chloro-4- cyclopropyl TFA 437.922 438.2 methoxyphenyl  10 N C(O) 3,5-dichlorophenyl cyclopropyl TFA 442.341 442.2  11 N C(O) 3-chlorophenyl cyclopropyl TFA 407.896 408.2  12 N C(O) 4-chlorophenyl cyclopropyl TFA 407.896 408.2  13 N CH₂ pyridin-3-yl cyclopropyl TFA 360.4555 361.3  14 N C(O) 2,3-dichlorophenyl cyclopropyl TFA 442.341 442.2  15 N C(O) 2-chlorophenyl cyclopropyl TFA 407.896 408.2  16 N C(O) 3-methylphenyl cyclopropyl TFA 387.4775 388.3  17 N CH₂ pyridin-4-yl cyclopropyl TFA 360.4555 361.2  18 N CH₂ 3-CF₃phenyl cyclopropyl TFA 427.4654 428.3  19 N CH₂ 4-chlorophenyl cyclopropyl TFA 393.9124 394.2  20 N CH₂ pyridin-2-yl cyclopropyl TFA 360.4555 361.2  21 N CH₂ 3-chlorophenyl 4- TFA 508.8406 509.2 bromophenyl  24 N CH₂ 3-chlorophenyl phenyl TFA 429.9445 430.2  25 N CH₂ 3-chlorophenyl 4-trifluoro- TFA 513.942 514.3 methoxyphenyl  26 N CH₂ 3-chlorophenyl 4-n- TFA 472.0243 472.3 propylphenyl  27 N C(O) 4-CF₃phenyl cyclopropyl TFA 441.4489 442.3  28 N CH₂ 2-chlorophenyl cyclopropyl TFA 393.9124 394.3  29 N CH₂ 4- cyclopropyl TFA 437.5578 438.3 methylsulfonylphenyl  30 N CH₂ 3-chlorophenyl 4-methyl- TFA 443.9711 444.25 phenyl  31 N CH₂ 3-chlorophenyl 4-methoxy- TFA 459.9706 560.3 phenyl  32 N CH₂ 3-chlorophenyl 2-methoxy- TFA 459.9706 460.3 phenyl  33 N CH₂ 2,5-dichlorophenyl cyclopropyl TFA 428.3575 428.2  34 N CH₂ 4-CF₃phenyl cyclopropyl TFA 427.4654 428.3  35 N CH₂ 3-chlorophenyl 3-methoxy- TFA 459.9706 460.3 phenyl  36 N CH₂ 3-chlorophenyl 4-tert-butyl- TFA 486.0509 486.3 phenyl  37 N CH₂ 3-chlorophenyl 4- TFA 488.0237 488.3 isopropoxy- phenyl  38 N CH₂ 3-chlorophenyl 4- TFA 447.935 448.3 fluorophenyl  39 N C(O) 2,5-dichlorophenyl cyclopentyl TFA 470.3942 470.3  40 N CH₂ 2,5-dichlorophenyl cyclopentyl TFA 456.4107 456.2  41 N C(O) 2,5-dichlorophenyl phenyl TFA 478.3731 478.2  42 N CH₂ 2,5-dichlorophenyl cyclopropyl- TFA 442.3841 442.2 methyl  43 N CH₂ 2,5-dichlorophenyl phenyl TFA 464.3896 464.2  45 N CH₂ 2,5-dichlorophenyl cyclopropyl 7-Br TFA 507.2536 508.15  46 N CH₂ 2,5-dichlorophenyl cyclopropyl 6-Br TFA 507.2536 508.1  47 N CH₂ 2,5-dichlorophenyl cyclopropyl 7- TFA 458.3835 458.2 OCH₃  48 N CH₂ 2,3-dichlorophenyl cyclopropyl TFA 428.3575 428.2  49 N CH₂ 2,4-dichlorophenyl cyclopropyl TFA 428.3575 428.2  50 N CH₂ 2,6-dichlorophenyl cyclopropyl TFA 428.3575 428.2  51 N CH₂ 3-chlorophenyl 3- TFA 508.8406 509.9 bromophenyl  52 N CH₂ 3-chlorophenyl 2- TFA 508.8406 510 bromophenyl  53 N CH₂ 3-chlorophenyl pyridin-3-yl TFA 430.9326 431  54 N C(O) 2,5-dichlorothien-3-yl cyclopropyl 448.3688 448.2  55 N CH₂ 2,5-dichlorophenyl cyclopropyl 7-F 446.348 446.2  56 N CH₂ 2,5-dichlorophenyl 3-methoxy- 494.4156 494.2 phenyl  57 N CH₂ 2,5-dichlorophenyl 4-methoxy- 494.4156 494.2 phenyl  58 N CH₂ 2,5-dichlorophenyl 4- 489.3991 489.2 cyanophenyl  59 N CH₂ 2,5-dichlorophenyl cyclopropyl 6-CN 453.367 453.2  60 N CH₂ 2,5-dichlorophenyl 2-methoxy- 494.4156 494.2 phenyl  61 N CH₂ 2,5-dichlorophenyl 4- 482.3801 482.2 fluorophenyl  62 N C(CCH₃) 2,5-dichlorophenyl cyclopropyl TFA 442.3841 443.2  64 N CH₂ 2,5-dichlorophenyl 4- 543.2857 544.15 bromophenyl  65 N CH₂ 3-bromophenyl cyclopropyl 438.3635 438.2/ 440.2  66 N CH₂ 2,5-dichlorophenyl 3- 460.3994 461.2 methoxypropyl  67 N CO(O) 2-chloro-4- cyclopropyl 485.9864 486.2 methylsulfonylphenyl  68 N C(O) 3,6-dichloropyridin- cyclopropyl 443.3291 443.2 2-yl  69 N C(O) benzofuran-3-yl cyclopropyl TFA 413.4717 414.30  70 N CH₂ 3-chlorophenyl pyridin-4-yl TFA 430.9326 431.1  71 N CH₂ 3-chlorophenyl thia[1,3,4]diazol- TFA 437.9484 438 2-yl  72 N C(O) 3,4-dimethylphenyl cyclopropyl TFA 401.5041 402.1  73 N CH₂ 3,4-dimethylphenyl cyclopropyl TFA 387.5206 388.1  74 N C(O) 2,4-dichlorophenyl cyclopropyl TFA 442.341 442  75 N C(O) 4-cyanophenyl cyclopropyl TFA 398.4604 399.1  76 N CH₂ 4-cyanophenyl cyclopropyl TFA 384.4769 384.9  77 N C(O) 4-ethylphenyl cyclopropyl TFA 401.5041 402.1  78 N CH₂ 4-ethylphenyl cyclopropyl TFA 387.5206 388.1  79 N CH₂ 3,4-dichlorophenyl cyclopropyl TFA 428.3575 427.9  80 N C(O) 2,5-difluorophenyl cyclopropyl TFA 409.4319 410  81 N CH₂ 2,5-difluorophenyl cyclopropyl TFA 395.4483 396  82 N C(O) naphth-2-yl cyclopropyl TFA 423.5096 424.1  83 N CH₂ naphth-2-yl cyclopropyl TFA 409.5261 410  84 N C(O) 4-tert-butylphenyl cyclopropyl TFA 429.5573 430.3  85 N C(O) 2-bromo-5- cyclopropyl TFA 482.373 482 methoxyphenyl  86 N C(O) 3-bromo-4- cyclopropyl TFA 482.373 482 methoxyphenyl  87 N C(O) 4-bromo-2- cyclopropyl TFA 486.7921 488 chlorophenyl  88 N C(O) 5-fluoro-2- cyclopropyl TFA 405.468 406 methylphenyl  89 N C(O) 3-bromo-4- cyclopropyl TFA 470.3374 472 fluorophenyl  90 N C(O) 4-bromo-2- cyclopropyl TFA 470.3374 470 fluorophenyl  91 N C(O) 5-bromo-2- cyclopropyl TFA 470.3374 470 fluorophenyl  92 N C(O) 4-ethoxyphenyl cyclopropyl TFA 417.5035 418.1  93 N C(O) 3-isopropylphenyl cyclopropyl TFA 415.5307 416.1  94 N CH₂ 4-bromophenyl cyclopropyl TFA 438.3635 439.7  95 N CH₂ 3-cyanophenyl cyclopropyl TFA 384.4769 385  96 N CH₂ 4-fluorophenyl cyclopropyl TFA 377.4579 378  97 N CH₂ 4-isopropylphenyl cyclopropyl TFA 401.5471 402.1  98 N C(O) 5-methylisoxazol-3- cyclopropyl 378.4277 379.3 yl  99 N CH₂ 2,5-dichlorothien-3-yl cyclopropyl TFA 434.3853 434.1 100 N CH₂ benzofuran-3-yl cyclopropyl 399.4882 400.30 101 N CH₂ 3,6-dichloropyridin- cyclopropyl TFA 429.3456 429.3 yl 102 N C(O) cyclohexyl cyclopropyl 379.4986 380.3 103 N CH₂ 2,5-dichlorophenyl cyclopropyl 5-CH₃ 456.4107 456.25 7-CH₃ 104 N CH₂ 2,5-dichlorophenyl cyclopropyl 6-CH₃ 456.4107 456.2 8-CH₃ 105 N SO₂ phenyl cyclopropyl 409.5046 410.3 106 N (CH₂)₂ phenyl cyclopropyl 373.494 374.30 107 N (CH₂)₂ 4-chlorophenyl cyclopropyl 407.939 408.30 108 N (CH₂)₂ 4-methoxyphenyl cyclopropyl 403.52 404.35 109 N CH₂ cyclohexyl cyclopropyl 365.515 366.4 110 N CH₂ 2,5-dichlorophenyl isobutyl TFA 444.4 444 111 N CH₂ 2,5-dichlorophenyl isopropyl TFA 430.3734 430.1 112 N CH₂ 2,5-dichlorophenyl 2-ethylbutyl TFA 472.4531 472.1 113 N CH₂ 2,5-dichlorophenyl 4- TFA 472.4531 472.2 methylpentan- 2-yl 114 N CH₂ 2,5-dichlorophenyl 2,2- TFA 458.4266 458.2 dimethylpropyl 115 N CH₂ 2,5-dichlorophenyl 3- TFA 458.4266 458.1 methylbutyl 116 N CH₂ 2,5-dichlorophenyl but-2-yl TFA 444.4 444.1 117 N CH₂ 2,5-dichlorophenyl n-propyl TFA 430.3734 430 118 N CH₂ 2,5-dichlorophenyl 2- TFA 446.3728 446 methoxyethyl 119 N CH₂ 2,5-dichlorophenyl cyclobutyl TFA 442.3841 441.9 120 N CH₂ 2,5-dichlorophenyl cyclopropyl 5-Br 507.2536 508.1 121 N C(O) 4-isopropylphenyl cyclopropyl TFA 415.5307 416.1 122 N C(O) 4-bromo-2- cyclopropyl TFA 466.3736 468 methylphenyl 123 N C(O) 2-chloro-3,6- cyclopropyl TFA 443.8769 444 difluorophenyl 124 N SO₂ 4-OCF₃phenyl cyclopropyl 493.502 494.2 125 N CH₂ 3-chlorophenyl thiazol-2-yl TFA 436.9603 437 126 N CH₂ 3-chlorophenyl pyrimidin-2- TFA 431.9207 432 yl 127 N CH₂ 3-chlorophenyl primidin-5- TFA 431.9207 432 yl 128 N SO₂ cyclopentyl cyclopropyl 401.5257 402.3 129 N CH₂ 5-fluoro-2- cyclopropyl TFA 391.4844 391.9 methylphenyl 130 N C(O) 2-chloro-5- cyclopropyl TFA 533.7925 533.94 iodophenyl 131 N C(O) 5-bromo-2- cyclopropyl TFA 466.3736 468.2 methylphenyl 132 N C(O) 4-OCF₃phenyl cyclopropyl TFA 457.4483 458.04 134 N CH₂ 2,5-dichlorophenyl cyclopropyl 8-Br TFA 507.2536 508.1 135 N C(O) indol-6-yl cyclopropyl TFA 412.487 413 136 N C(O) 5-chloro-2- cyclopropyl TFA 421.9225 422.03 methylphenyl 137 N C(O) 4-chloro-2- cyclopropyl TFA 421.9225 422.04 methylphenyl 138 N C(O) 2,4-dimethylphenyl cyclopropyl TFA 401.5041 402.04 139 N C(O) 2-chloro-5- cyclopropyl TFA 437.922 438 methoxyphenyl 140 N C(O) 3-cyano-4- cyclopropyl TFA 456.5395 457.07 isopropoxyphenyl 141 N C(O) 2-methoxy-5- cyclopropyl TFA 487.4743 488.04 trifluoromethoxy- phenyl 142 N C(O) 2,3,5-trichlorophenyl cyclopropyl TFA 476.7861 476.01 143 N C(O) 2-chloro-6- cyclopropyl TFA 475.894 476 trifluoromethylphenyl 144 N (CH₂)₂ 2,5-dichlorophenyl cyclopropyl 442.3841 443.25 145 N CH₂ 2,5-dichlorophenyl pyridin-3-yl 465.3777 466.25 146 N C(O) 4- cyclopropyl TFA 421.9225 422 chloromethylphenyl 147 N C(O) indol-5-yl cyclopropyl TFA 412.487 413.1 148 N C(O) 4-bromo-3- cyclopropyl TFA 466.3736 468 methylphenyl 149 N CH₂ 2-chloro-4- cyclopropyl TFA 472.0028 472.2 methylsulfonylphenyl 151 N CH₂ 2,5-dichlorophenyl cyclopropyl 7-CN TFA 453.367 453.2 152 N C(O) 4-fluoro-3- cyclopropyl TFA 421.4674 422.1 methoxyphenyl 153 N C(O) 3-bromo-4- cyclopropyl TFA 466.3736 methylphenyl 154 N C(O) 4-chloro-3- cyclopropyl TFA 421.9225 422 methylphenyl 155 N C(O) 4-fluoro-2- cyclopropyl 405.468 406 methylphenyl 156 N CH₂ 4-fluoro-2- cyclopropyl TFA 391.4844 392 methylphenyl 157 N CH₂ 5-methylisoxazol-3- cyclopropyl TFA 364.4442 365.3 yl 158 N CH₂ 2,5-dichlorophenyl pyridin-3-yl 7-CN 490.3871 490.2 159 N C(O) 4-chlorophenyl cyclopropyl 6-CN 432.9054 433.25 160 N C(O) 4-chlorophenyl cyclopropyl 6-F 425.8864 426.20 161 N SO₂ phenyl cyclopropyl 6-CN 434.5141 435.30 162 N SO₂ phenyl pyridin-3-yl H 446.5248 447.30 163 N CH₂ 3-chlorophenyl cyclopropyl 6-CN 418.9219 419.25 164 N CH₂ 2,5-dichlorophenyl tert-butyl TFA 444.4 444 165 N CH₂ 2,5-dichlorophenyl 3,3- TFA 472.4531 472.1 dimethylbutyl 166 N CH₂ 2,5-dichlorophenyl 2-ethoxyethyl TFA 460.3994 460 167 N CH₂ 2,5-dichlorophenyl 2- TFA 474.426 474.1 isopropoxyethyl 168 N CH₂ 2,5-dichlorophenyl 3- TFA 474.426 474.1 ethoxypropyl 169 N CH₂ 2,5-dichlorophenyl cyclohexyl TFA 470.4373 470.1 170 N CH₂ 2,5-dichlorophenyl tetrahydropyran- TFA 472.4101 472 4-yl 171 N CH₂ 2,5-dichlorophenyl (R)-3- TFA 446.3728 446 hydroxyprop- 2-yl 172 N CH₂ 2,5-dichlorophenyl pyrazin-2-yl TFA 466.3658 466 173 N CH₂ 2,5-dichlorophenyl pyrimidin-4- TFA 466.3658 466 yl 174 N CH₂ 2,5-dichlorophenyl pyridazin-3- TFA 466.3658 466 yl 175 N CH₂ 2,5-dichlorophenyl pyridin-3-yl 6-F TFA 483.3681 483.25 176 N CH₂ 2,5-dichlorophenyl 1,2,4-triazin- TFA 467.3538 467.1 3-yl 177 N CH₂ 2,5-dichlorophenyl 5,6-dimethyl- TFA 495.407 495.3 1,2,4-triazin- 3-yl 178 N CH₂ 2,5-dichlorophenyl 3,4- TFA 483.393 483 dimethylisoxazol- 5-yl 179 N C(O) 3-bromo-2- cyclopropyl TFA 466.3736 468.1 methylphenyl 180 N C(O) 3,5-difluorophenyl cyclopropyl TFA 409.4319 410.1 181 N C(O) 4-bromophenyl cyclopropyl TFA 452.347 454 182 N C(O) 3-cyanophenyl cyclopropyl TFA 398.4604 399.1 183 N C(O) 3-bromophenyl cyclopropyl TFA 452.347 453.6 184 N C(O) 2,6-dichlorophenyl cyclopropyl TFA 442.341 441.8 185 N C(O) 2-bromo-4-methyl- cyclopropyl TFA 466.3736 468 phenyl 186 N C(O) 4-cyano-2-fluoro- cyclopropyl TFA 416.4508 417.1 phenyl 187 N C(O) benzo[d][1,2,3]thiadiazol cyclopropyl TFA 431.5134 432 5-yl 188 N C(O) 2-chloro-5-fluoro- cyclopropyl TFA 425.8864 425.9 phenyl 189 N C(O) 2,6-difluorophenyl-3- cyclopropyl TFA 423.4584 424.2 methylphenyl 190 N C(O) 2-methoxy-5- cyclopropyl TFA 471.4749 471.9 trifluoromethylphenyl 191 N C(O) 4-bromo-3- cyclopropyl 520.345 521.8 trifluoromethylphenyl 192 N CH₂ 3,5-difluorophenyl cyclopropyl TFA 395.4483 395.9 193 N CH₂ 4-chloro-3-methyl- cyclopropyl TFA 407.939 407.9 phenyl 194 N CH₂ 2,3-dimethylphenyl cyclopropyl TFA 387.5206 388.1 195 N CH₂ 2-bromo-5- cyclopropyl TFA 468.3894 469.8 methoxyphenyl 196 N CH₂ 3-bromo-4- cyclopropyl TFA 468.3894 469.7 methoxyphenyl 197 N CH₂ 4-bromo-2- cyclopropyl TFA 472.8085 473.7 chlorophenyl 198 N CH₂ 3-bromo-4- cyclopropyl TFA 456.3539 455.8 fluorophenyl 199 N CH₂ 4-bromo-2- cyclopropyl TFA 456.3539 457.8 fluorophenyl 200 N CH₂ 5-bromo-2- cyclopropyl TFA 456.3539 457.6 fluorophenyl 201 N CH₂ 5-bromo-2- cyclopropyl TFA 452.39 453.7 methylphenyl 202 N CH₂ indol-6-yl cyclopropyl TFA 398.5034 398.9 203 N CH₂ 5-chloro-2-methyl- cyclopropyl TFA 407.939 407.9 phenyl 204 N CH₂ 4-chloro-2-methyl- cyclopropyl TFA 407.939 408.1 phenyl 205 N CH₂ 2-chloro-3,6- cyclopropyl TFA 429.8934 429.9 difluorophenyl 206 N CH₂ 2,4-dimethylphenyl cyclopropyl TFA 387.5206 388 207 N CH₂ 2-chloro-5- cyclopropyl TFA 423.9384 423.9 methoxyphenyl 208 N CH₂ 2-chloro-5-fluoro- cyclopropyl TFA 411.9029 411.9 phenyl 209 N CH₂ 2-chloro-6- cyclopropyl TFA 461.9104 462.1 trifluoromethylphenyl 210 N CH₂ 3-isopropylphenyl cyclopropyl TFA 401.5471 401.9 211 N SO₂ phenyl cyclopropyl 6-F 427.4951 428.25 112 N CH₂ 2,5-difluorophenyl cyclopropyl 6-F 413.4388 414.30 213 N CH₂ 2,5-dichlorophenyl pyridin-4-yl TFA 465.3777 465 214 N CH₂ 2,5-difluorophenyl cyclopropyl 6-F TFA 431.4293 432 7-F 215 N CH₂ 3-chloro-4- cyclopropyl TFA 423.9384 423.9 methoxyphenyl 216 N CH₂ 4-bromo-3- cyclopropyl TFA 452.39 451.9 methylphenyl 217 N CH₂ 4-bromo-2- cyclopropyl TFA 452.39 453.9 methylphenyl 218 N CH₂ 2-chloro-5- cyclopropyl TFA 519.809 519.8 iodophenyl 219 N CH₂ 2-methoxy-5- cyclopropyl TFA 473.4908 473.9 trifluoromethoxy- phenyl 220 N CH₂ 2,3,5-trichlorophenyl cyclopropyl TFA 462.8026 463.6 221 N CH₂ 2-chloro-5- cyclopropyl TFA 412.891 413 fluoropyridin-3-yl 222 N C(O) 4-chlorophenyl pyridin-3-yl TFA 444.9161 445.20 223 N SO₂ 3-chlorophenyl cyclopropyl 6-CN 468.9591 469.20 224 N SO₂ 3-chlorophenyl cyclopropyl 6-F 461.9402 462.20 225 N SO₂ 2,5-dichlorophenyl cyclopropyl 6-CN 503.4042 504.20 226 N SO₂ 4-chlorophenyl cyclopropyl 6-CN TFA 468.9591 469.2 227 N CH₂ 2,5-dichlorophenyl pyridin-2-yl TFA 465.3777 465 228 N CH₂ 2,5-difluorophenyl pyridin-3-yl TFA 432.4685 433.1 229 N C(O) 4-chloro-3- pyridin-3-yl TFA 458.9427 459.1 methylphenyl 230 N CH₂ 2,5-dichlorophenyl cyclopropyl 6-F TFA 464.3384 464 7-F 231 N C(O) 3-bromoo-4- cyclopropyl 6-F TFA 506.3184 507.8 fluorophenyl 7-F 232 N CH₂ 2-bromo-5- cyclopropyl TFA 472.8085 473.8 chlorophenyl 233 N CH₂ 5-chloro-2- cyclopropyl TFA 461.9104 462.1 trifluoromethylphenyl 234 N CH₂ 2,6-difluoro-3- cyclopropyl TFA 409.4749 410.1 methylphenyl 235 N CH₂ 2-methoxy-5- cyclopropyl TFA 457.4914 458.1 trifluoromethylphenyl 236 N SO₂ 2-methylphenyl cyclopropyl 6-CN 448.5406 449.30 237 N SO₂ 3-fluorophenyl cyclopropyl 6-CN TFA 452.5045 453.1 238 N SO₂ 3-methylphenyl cyclopropyl 6-CN 448.5406 449.30 239 N SO₂ 4-methylphenyl cyclopropyl 6-CN 448.5406 449.30 240 N SO₂ 2-fluorophenyl cyclopropyl 6-CN TFA 452.5045 453.2 241 N CH₂ 2,5-dichlorophenyl cyclopropyl 5-CN TFA 453.367 453.25 242 N C(O) 4-chlorophenyl cyclopropyl 6-F 443.8769 444.2 7-F 243 N SO₂ 2-chlorophenyl cyclopropyl 6-CN TFA 468.9591 469.2 244 N SO₂ 4-fluorophenyl cyclopropyl 6-CN TFA 452.5045 453.3 245 N CH₂ 3-chlorophenyl cyclopropyl 6-F TFA 429.8934 430.3 7-F 246 N C(O) 4-bromo-3- cyclopropyl 6-F 488.3279 489.25 fluorophenyl 247 N CH₂ 2,5-dichlorophenyl cyclopropyl 8-CN TFA 453.367 453.2 248 N SO₂ 2-bromophenyl cyclopropyl 6-CN 513.4102 514.20 249 N SO₂ 3-bromophenyl cyclopropyl 6-CN 513.4102 514.10 250 N SO₂ 4-bromophenyl cyclopropyl 6-CN 513.4102 514.20 251 N SO₂ 2-cyanophenyl cyclopropyl 6-CN TFA 459.5235 460.3 252 N SO₂ 3-cyanophenyl cyclopropyl 6-CN TFA 459.5235 460.3 253 N SO₂ 4-cyanophenyl cyclopropyl 6-CN TFA 459.5235 460.3 254 N CH₂ 4-fluorophenyl cyclopropyl 6-CN 402.4673 403.30 255 N C(O) 3-bromo-4- cyclopropyl 6-CN TFA 495.3469 496.8 fluorophenyl 256 N CH₂ 2,5-difluorophenyl cyclopropyl 6-CN TFA 420.4578 420.9 257 N CH₂ 2,5-dichlorophenyl isopropyl 6-CN TFA 455.3829 455 258 N CH₂ 2,5-difluorophenyl isopropyl 6-CN TFA 422.4737 423 259 N C(O) 3-bromo-4- isopropyl 6-CN TFA 497.3628 498.8 fluorophenyl 260 N CH₂ 2,5-difluorophenyl cyclobutyl 6-CN TFA 434.4844 435.1 261 N C(O) 3-bromo-4- cyclobutyl 6-CN TFA 509.3735 508.8 fluorophenyl 264 N C(O) 2,5-dichloropyridin- cyclopropyl 6-CN 468.3386 468.2 yl 265 N C(O) 4-chlorophenyl cyclobutyl 6-CN 446.932 447.30 266 N C(O) 4-chlorophenyl isopropyl 6-CN 434.9213 435.30 268 N CH₂ 2,5-dichlorophenyl 2,2,2- TFA 470.3182 469.8 trifluoroethyl 269 N SO₂ 3,5-dimethylisoxazol- cyclopropyl 6-CN TFA 453.5174 454 4-yl 270 N SO₂ 2,5-dimethylphenyl cyclopropyl 6-CN TFA 462.5672 463.1 271 N SO₂ 4-methoxyphenyl cyclopropyl 6-CN TFA 464.5401 465.1 272 N SO₂ 2-methoxyphenyl cyclopropyl 6-CN TFA 464.5401 465.1 273 N SO₂ 3-methoxyphenyl cyclopropyl 6-CN TFA 464.5401 465.1 274 N SO₂ 5-chlorothien-2-yl cyclopropyl 6-CN TFA 474.9868 474.9 275 N SO₂ 2,4,6-trimethylphenyl cyclopropyl 6-CN TFA 476.5938 477.1 276 N SO₂ 2-methoxy-4- cyclopropyl 6-CN TFA 478.5667 479 methylphenyl 277 N SO₂ 5-chloro-1,3- cyclopropyl 6-CN TFA 486.9777 487.1 dimethylpyrazol-4-yl 278 N SO₂ 2,3,4-trifluorophenyl cyclopropyl 6-CN TFA 488.4855 489.1 279 N SO₂ 4-tert-butylphenyl cyclopropyl 6-CN TFA 490.6204 491.1 280 N SO₂ 4-chloro-2-5- cyclopropyl 6-CN TFA 497.0123 497.1 dimethylphenyl 281 N SO₂ 3-chloro-5-fluoro-2- cyclopropyl 6-CN TFA 500.9762 501 methylphenyl 282 N SO₂ 4-trifluoro- cyclopropyl 6-CN TFA 518.5115 519.3 methoxyphenyl 283 N SO₂ 5-bromothien-2-yl cyclopropyl 6-CN TFA 519.4379 520.8 284 N SO₂ 4-bromo-2- cyclopropyl 6-CN TFA 531.4006 532.7 fluorophenyl 285 N SO₂ 2-chloro-5-trifluoro- cyclopropyl 6-CN TFA 536.9571 537 methylphenyl 286 N SO₂ 4-bromo-2- cyclopropyl 6-CN TFA 547.8552 548.9 chlorophenyl 293 N CH₂ 2,6-dichlorophenyl cyclopropyl 6-CN TFA 453.367 453.2 294 N C(O) 4-chlorophenyl cyclobutylmethyl 6-CN 295 N C(O) 2,5-dichlorophenyl cyclobutylmethyl 6-CN 296 N C(O) 2,5-dichloropyridin- cyclopropyl 6-CN TFA 468.3386 468.2 3-yl 297 N C(O) 4-chlorophenyl oxetan-3-yl 6-CN 429.3456 429.2 299 N CH₂ 2,5-dichlorophenyl oxetan-3-yl 6-CN 302 N C(O) 4-chlorophenyl cyclopropyl 7-CN TFA 432.9054 433.2 304 N CH₂ 2,5-difluorophenyl cyclopropyl 7-CN TFA 420.4578 421.3 307 N SO₂ 4-fluorophenyl cyclopropyl 7-CN TFA 452.5045 453.2 308 N CH₂ 2,5-dichlorophenyl pyridin-3-yl 6-CN TFA 490.3871 490.2 310 N CH₂ 2,5-difluorophenyl pyridine-3-yl 6-CN 457.4779 458.3 312 N CH₂ 2,5-difluorophenyl

6-CN 313 N CH₂ 2,5-dichlorophenyl

6-CN 319 N CH₂ 2,5-difluorophenyl

6-CN 320 N SO₂ 4-ethylphenyl cyclopropyl 6-CN TFA 462.5672 462.9 321 N CH₂ 2,5-difluorophenyl

6-CN 322 N SO₂ 2-fluoro-5-methyl- cyclopropyl 6-CN TFA 466.5311 467.2 phenyl 323 N C(O) 4-chlorophenyl

6-CN 324 N CH₂ 2,5-difluorophenyl

6-CN 325 N SO₂ 3,4-difluorophenyl cyclopropyl 6-CN TFA 470.495 470.9 326 N C(O) 4-chlorophenyl

6-CN 327 N C(O) 4-chlorophenyl pyridin-3-yl 6-CN 469.9256 470.2 328 N SO₂ 2,5-dimethoxyphenyl cyclopropyl 6-CN TFA 494.566 495.1 329 N SO₂ 2-chloro-4-trifluoro- cyclopropyl 6-CN TFA 536.9571 537 methylphenyl 332 N CH₂ 2,5-difluorophenyl 6- 6-CN TFA 487.5039 488.30 methoxypyridin- 3-yl 333 N CH₂ 2,5-dichlorophenyl 1- 6-CN TFA 481.3771 481.2 oxocyclobut- 3-yl 334 N CH₂ 2,5-difluorophenyl 1- 6-CN TFA 448.4679 449.3 oxocyclobut- 3-yl 335 N CH₂ 2,5-dichlorophenyl cyclobutyl 6-CN TFA 467.3936 467 336 N C(O) 4-chlorophenyl 2-fluoroethyl 6-CN TFA 438.8852 438.8 337 N CH₂ 2,5-dichlorophenyl 2,2- 6-CN 477.3372 476.8 difluoroethyl 338 N C(O) 4-chlorophenyl 2,2- 456.8757 457.1 difluoroethyl 339 N CH₂ 2,5-dichlorophenyl isoxazol-3-yl 6-CN TFA 480.3493 479.8 340 N C(O) 4-chlorophenyl isoxazol-3-yl 6-CN TFA 459.8877 460 341 N SO₂ 3-cyano-4-fluoro- cyclopropyl 6-CN TFA 477.514 478 phenyl 342 N CH₂ 2,4-difluorophenyl cyclopropyl 6-CN TFA 420.4578 421.3 343 N SO₂ 5-chloro-2- cyclopropyl 6-CN TFA 498.9851 499 methoxyphenyl 344 N SO₂ 5-chloro-2,4- cyclopropyl 6-CN TFA 504.9401 505 difluorophenyl 345 N SO₂ 5-bromo-6- cyclopropyl 6-CN TFA 548.8433 549.9 chloropyridin-3-yl 346 N SO₂ 4-bromo-2,5- cyclopropyl 6-CN TFA 549.3911 550.8 difluorophenyl 347 N CH₂ 2,5-dichlorophenyl 2-fluoroethyl 6-CN TFA 459.3467 459 348 N CH₂ 2,5-difluorophenyl 2-fluoroethyl 6-CN TFA 426.4376 426.9 349 N CH₂ 2,5-difluorophenyl 2,2- 6-CN TFA 444.428 444.9 difluoroethyl 352 N CH₂ 2,4,5-trifluorophenyl cyclopropyl 6-CN TFA 438.4482 439.2 357 N SO₂ 2,4-dimethoxyphenyl cyclopropyl 6-CN 494.566 494.9 367 N CH₂ 5-chloro-2-fluoro- cyclopropyl 6-CN TFA 436.9124 437.2 phenyl 371 N CH₂ 2,4-difluorophenyl pyridin-3-yl 6-CN TFA 457.4779 458.30 373 N CH₂ 2,4-difluorophenyl cyclopropyl 7-CN TFA 420.4578 421.25 374 N CH₂ 5-chloro-2-fluoro- cyclopropyl 7-CN TFA 436.9124 437.20 phenyl 375 N CH₂ 2,4,5-trifluorophenyl cyclopropyl 7-CN TFA 438.4482 439.30 376 N CH₂ 2,4,5-trifluorophenyl pyridin-3-yl 6-CN TFA 475.4684 476.30 377 N C(O) 4-chloro-2-fluoro- pyridin-3-yl 6-CN TFA 487.9161 488.20 phenyl 378 N CH₂ 2,5-difluorophenyl isoxazol-3-yl 6-CN 447.4401 448 399 N CH₂ 2,5-difluorophenyl 3,3,3- 6-CN TFA 476.4451 477.3 trifluoropropyl 400 N CH₂ 2,4-difluorophenyl 3,3,3- 6-CN TFA 476.4451 477.2 trifluoropropyl 401 N CH₂ 2,5-difluorophenyl cyclopropyl 6-Br TFA 474.3444 474.2/ 476.2 402 N CH₂ 5-chloro-2- cyclopropyl 6-Br TFA 490.799 490.1/ fluorophenyl 492.1 403 N CH₂ 2,4-difluorophenyl cyclopropyl 6-Br TFA 474.3444 474.2/ 476.2 404 N CH₂ 2,4-difluorophenyl 2,2- 6-CN 444.428 445.2 difluoroethyl 407 N CH₂ 2,4-difluorophenyl 2- 6-CN TFA 438.4731 439.3 methoxyethyl 408 CH CH₂ 5-methyloxazol-2-yl cyclopropyl TFA 363.4561 364.3 409 CH CH₂ 3-methyl-[1,2,4]- cyclopropyl TFA 364.4442 365.3 oxadiazol-5-yl 410 CH CH₂ phenyl phenyl TFA 394.5114 395.1 411 CH O phenyl cyclopropyl 360.4521 361.30 412 CH NH 4-chlorophenyl cyclopropyl TFA 393.9124 394.3 414 CH CH₂ 2,4-difluorophenyl pyridin-3-yl 6-CN TFA 456.4899 457.30 415 CH CH₂ 2,4-difluorophenyl cyclopropyl 6-CN TFA 419.4697 420.3 462 CH CH₂ 2,4-difluorophenyl isopropyl 6-CN 421.4856 422.3 463 CH CH₂ 2,4-difluorophenyl cyclobutyl 6-CN 433.4963 434.3 466 CH O 4-chloro-2- cyclopropyl 6-CN TFA 437.8972 438.20 fluorophenyl 467 CH O 4-chloro-2- isopropyl 6-CN TFA 439.913 440.20 fluorophenyl 469 CH O 2,4-difluorophenyl cyclopropyl 6-CN TFA 421.4425 422.20 470 CH C(O) 5-chloro-2- cyclopropyl 6-CN TFA 449.9078 450.20 fluorophenyl 471 CH CHF 2,5-difluorophenyl cyclopropyl 6-CN TFA 437.4602 438.3 472 CH CH₂

cyclopropyl 6-CN TFA 418.4667 419.2 473 CH C(O) 2,5-difluorophenyl cyclopropyl 6-CN TFA 433.4532 434.2 475 CH O 4-chloro-2- cyclopropyl 7-CN TFA 437.8972 438.20 fluorophenyl 479 CH CH₂ 2,4-difluorophenyl cyclopropyl 6-F TFA 430.4412 431.25 7-F 480 CH CH₂ 2,4-difluorophenyl cyclopropyl 6-F TFA 412.4507 413.30 481 CH CHF 2,4-difluorophenyl cyclopropyl 6-CN TFA 437.4602 438.20 482 CH CHF 2,4-difluorophenyl isopropyl 6-CN TFA 439.4761 440.30 483 CH CHF 2,5-difluorophenyl cyclobutyl 6-CN TFA 451.4868 452.3 485 CH CHF 2,5-difluorophenyl cyclopropyl 7-CN TFA 437.4602 438.3 486 CH CHF 2,5-difluorophenyl isopropyl 6-CN TFA 439.4761 440.3 488 CH CHF 2,4-difluorophenyl cyclopropyl 7-CN TFA 437.4602 438.30 492 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 6-CN TFA 437.4602 438.20 496 CH CH₂ 2,4-difluorophenyl cyclopropyl 6-Br TFA 473.3563 473.3/ 475.2 497 CH CH₂ 2,4-difluorophenyl 3,3,3- 6-CN TFA 475.457 476.3 trifluoropropyl 499 CH CHF 2,5-difluorophenyl 3,3,3- 6-CN TFA 493.4474 494.3 trifluoropropyl 500 CH O 2,4-difluorophenyl 3,3,3- 6-CN TFA 477.4298 478.2 trifluoropropyl 501 CH CHF 2,5-difluorophenyl cyclopropyl 6-Br TFA 491.3468 491.2/ 493.2 502 CH O 2,4-difluorophenyl cyclopropyl 6-Br TFA 475.3291 475.2/ 477.2 504 CH (S)—CHF 2,5-difluorophenyl isopropyl 6-CN 439.4761 440.1 505 CH (R)—CHF 2,5-difluorophenyl isopropyl 6-CN 439.4761 440.1 506 CH (S)—CHF 2,4-difluorophenyl cyclopropyl 6-CN 437.4602 438.2 507 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 6-CN 437.4602 438.1 508 CH (S)—CHF 2,4-difluorophenyl isopropyl 6-CN 439.4761 440.1 509 CH (R)—CHF 2,4-difluorophenyl isopropyl 6-CN 439.4761 440 510 CH (S)—CHF 2,4-difluorophenyl cyclopropyl 7-CN 437.4602 438.1 511 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 7-CN 437.4602 438.1 512 CH CHF 2,4-difluorophenyl 2,2- 6-CN 461.4304 462.2 difluoroethyl 513 CH CH₂ 2,4-difluorophenyl 2,2- 6-CN 443.4399 444.2 difluoroethyl 514 CH O 2,4-difluorophenyl 2,2- 6-CN 445.4128 446.2 difluoroethyl 515 CH (S)—CHF 2,4-difluorophenyl cyclopropyl 6-CN TFA 437.4602 438.3 519 CH CH₂ 2,4-difluorophenyl 2- 6-CN 437.485 438.3 methoxyethyl, 522 CH O 2,4-difluorophenyl 2- 6-CN 439.4578 440.25 methoxyethyl, 523 CH CHF 2,4-difluorophenyl 2- 6-CN 455.4755 456.3 methoxyethyl, 527 CH CH₂

cyclopropyl 6-CN 434.9213 435.2 530 CH CH₂

cyclopropyl 6-CN 418.4667 419.3 534 CH CF₂ 5-chloro-2- cyclopropyl 6-CN 471.9052 472.2 fluorophenyl 536 CH CH₂

cyclopropyl 6-CN 434.9213 435.3 546 CH CF₂ 2,4-difluorophenyl cyclopropyl 6-CN 455.4507 456.2 548 CH CF₂ 2,5-difluorophenyl cyclopropyl 6-CN 455.4507 456.3 627 CH O 2-fluoro-4- isopropyl HCl 438.373 439.8 chlorophenyl 628 CH C(O) 3-isopropylamino-5- isopropyl 7-CN 491.027 491.0 chlorophenyl

 3 N CH₂ 3-methylphenyl cyclopropyl 374.482 375.3  23 N CH₂ 3-chlorophenyl phenyl TFA 430.9326 431.2  63 N CH₂ 2,5-dichlorophenyl cyclopropyl 429.3456 429.2 150 N CH₂ 2,5-dichlorophenyl pyridin-3-yl TFA 466.3658 466.2

133 N CH₂ 2,5- cyclopropyl TFA 429.3456 429.2 dichlorophenyl 262 N C(O) 4-chlorophenyl cyclopropyl 408.884 409.25 263 N CH₂ 2,5-difluorophenyl cyclopropyl TFA 396.4364 397.3 267 N C(O) 4-trifluoromethyl- cyclopropyl TFA 442.437 443.3 phenyl 287 N SO₂ 4-fluorophenyl cyclopropyl TFA 428.4832 429.3 288 N C(O) 4-difluoromethyl- cyclopropyl TFA 424.4465 425.3 phenyl 289 N CH₂ 5-chloro-2- cyclopropyl TFA 460.9074 461.3 difluoro- methoxyphenyl 290 N CH₂ 4-fluorophenyl cyclopropyl TFA 378.4459 379.3 298 N CH₂ 2,6- cyclopropyl TFA 429.3456 429.2 dichlorophenyl 300 N CH₂ 5-chloro-2- cyclopropyl TFA 452.9796 453.3 propoxy-phenyl 301 N SO₂ 4-trifluoromethyl- cyclopropyl TFA 478.4907 479.3 phenyl 305 N CH₂ 2-methoxy-5-tert- cyclopropyl TFA 446.5878 447.4 butylphenyl 306 N CH₂ 2,5- cyclopropyl TFA 388.5086 389.3 dimethylphenyl 311 N CH₂ 2,6-difluorophenyl cyclopropyl TFA 396.4364 397.3 314 N CH₂ 3-chloro-4-fluoro- cyclopropyl TFA 412.891 413.3 phenyl 315 N CH₂ 2,4,5- cyclopropyl TFA 414.4268 415.3 trifluorophenyl 316 N CH₂ 4-chloro-3-fluoro- cyclopropyl TFA 412.891 413.3 phenyl 317 N CH₂ 3,4-difluorophenyl cyclopropyl TFA 396.4364 397.3 318 N CH₂ 2,4-difluorophenyl cyclopropyl TFA 396.4364 397.3 330 N CH₂ 5-chloro-2-fluoro- cyclopropyl TFA 412.891 413.3 phenyl 331 N CH₂ 2-chloro-5-fluoro- cyclopropyl TFA 412.891 413.2 phenyl 350 N CH₂ 5-chloro-2-fluoro- cyclopropyl 8-Cl TFA 447.336 448.20 phenyl 351 N CH₂ 2,5-difluorophenyl cyclopropyl 8-Cl TFA 430.8814 431.20 353 N CH₂ 2,4-difluorophenyl cyclopropyl 8-Cl TFA 430.8814 431.20 354 N CH₂ 2,4,5- cyclopropyl 8-Cl TFA 448.8719 449.20 trifluorophenyl 358 N C(O) 4-chloro-3-fluoro- cyclopropyl TFA 426.8745 427.2 phenyl 359 N C(O) 3,4-difluorophenyl cyclopropyl TFA 410.4199 411.3 360 N C(O) 3-chloro-4-fluoro- cyclopropyl TFA 426.8745 427.2 phenyl 361 N C(O) 4-chloro-2-fluoro- cyclopropyl TFA 426.8745 427.2 phenyl 362 N C(O) 2-chloro-4-fluoro- cyclopropyl TFA 426.8745 427.2 phenyl 365 N CH₂ 2,4-difluorophenyl 2,2- TFA 420.4066 421.20 difluoroethyl 366 N CH₂ 5-chloro-2-fluoro- 2,2- TFA 436.8612 437.20 phenyl difluoroethyl 368 N C(O) 4-chloro-2-fluoro- 2,2- TFA 450.8447 451.20 phenyl difluoroethyl 370 N CH₂ 2,4,5- 2,2 TFA 438.3971 439.20 trifluorophenyl difluoroethyl 372 N C(O) 4-chloro-2- cyclopropyl TFA 424.8835 425.2 hydroxy-phenyl 380 N C(O) 4-chloro-2- cyclopropyl TFA 438.91 439.2 methoxy-phenyl 381 N C(O) 2-fluoro-4- cyclopropyl TFA 460.4274 461.3 trifluoro- methylphenyl 382 N C(O) 3-fluoro-5- cyclopropyl TFA 427.8625 428.3 chloropyridin-2-yl 383 N C(O) 2-fluoro-4-methyl- cyclopropyl TFA 406.456 407.3 phenyl 384 N C(O) 2-fluoro-4- cyclopropyl TFA 422.4554 423.2 methoxy-phenyl 385 N C(O) 4-chloro-2- cyclopropyl TFA 422.9106 423.3 methyl-phenyl 386 N C(O) 4-cyano-2-fluoro- cyclopropyl TFA 417.4389 418.3 phenyl 387 N C(O) 4-fluoro-2- cyclopropyl TFA 408.4288 409.3 hydoxy-phenyl 388 N C(O) 4-chloro-2,6- cyclopropyl TFA 444.865 445.2 difluorophenyl 389 N C(O) 3-fluoropyridin-2- cyclopropyl TFA 393.4175 394.3 yl 391 N C(O) 4-chloro-2- cyclopropyl TFA 476.882 477.3 trifluoro- methylphenyl 393 N C(O) 2,4,6- cyclopropyl TFA 428.4104 429.3 trifluorophenyl 394 N C(O) 2,4-difluoro-6- cyclopropyl TFA 426.4193 427.3 hydroxyphenyl 395 N CH₂ 2,4-difluorophenyl cyclopropyl 7-CH₃ TFA 410.463 411.3 396 N CH₂ 5-chloro-2- cyclopropyl 7-CH₃ TFA 426.9176 427.3 fluorophenyl 405 N CH₂ 2,4-difluorophenyl cyclopropyl 7-Br TFA 475.3325 475.2/ 477.2 406 N CH₂ 2,4-difluorophenyl 2- TFA 414.4517 415.3 methoxyethyl 413 CH CH₂ 2,4-difluorophenyl cyclopropyl TFA 395.4483 396.3 416 CH O 2-chlorophenyl cyclopropyl TFA 395.8853 396.20 417 CH O 2-fluorophenyl cyclopropyl TFA 379.4307 380.25 418 CH O 3-fluorophenyl cyclopropyl TFA 379.4307 380.30 419 CH C(O) 4-fluorophenyl cyclopropyl TFA 391.4414 392.30 420 CH CH₂ 4-fluorophenyl cyclopropyl TFA 377.4579 378.30 421 CH C(O) 3,4-difluorophenyl cyclopropyl TFA 409.4319 410.30 422 CH SO₂ 4-fluorophenyl cyclopropyl TFA 427.4951 428.30 423 CH CH₂ 4-chlorophenyl cyclopropyl TFA 393.9124 394.30 424 CH O 4-chlorophenyl cyclopropyl TFA 395.8853 396.30 425 CH O 3-chlorophenyl cyclopropyl TFA 395.8853 396.25 428 CH CH₂ 2,4-difluorophenyl cyclopropyl 7-CH₃ TFA 409.47 410.3 429 CH C(O) 4-chlorophenyl cyclopropyl TFA 407.896 408.30 430 CH O 2,5-difluorophenyl cyclopropyl TFA 397.4211 398.30 431 CH O 2,4,6- cyclopropyl TFA 415.4116 416.30 trifluorophenyl 432 CH O 4-fluorophenyl cyclopropyl TFA 379.4307 380.30 433 CH O 2,4-difluorophenyl cyclopropyl TFA 397.4211 398.20 434 CH C(O) 2-fluorophenyl cyclopropyl TFA 391.4414 392.25 435 CH C(O) 2,5-difluorophenyl cyclopropyl TFA 409.4319 410.25 436 CH O 5-chloro-2- cyclopropyl TFA 413.8757 414.20 fluorophenyl 437 CH O phenyl cyclopropyl TFA 361.4402 362.25 438 CH C(O) 2,4-difluorophenyl cyclopropyl TFA 409.4319 410.30 440 CH C(O) 2,5-difluorophenyl cyclopropyl 7-CH₃ TFA 423.4584 424.3 441 CH O 2,4-difluorophenyl cyclopropyl 7-CH₃ TFA 411.4477 412.3 442 CH O 4-chloro-2- cyclopropyl TFA 413.8757 414.20 fluorophenyl 443 CH C(O) 2,4,6- cyclopropyl TFA 427.4223 428.25 trifluorophenyl 444 CH C(O) 4-chloro-2,6- cyclopropyl TFA 443.8769 444.20 difluorophenyl 445 CH CH₂ 2,5-difluorophenyl cyclopropyl TFA 395.4483 396.3 446 CH C(O) 4-chloro-2- cyclopropyl TFA 425.8864 426.20 fluorophenyl 447 CH C(O) 5-chloro-2- cyclopropyl TFA 425.8864 426.20 fluorophenyl 448 CH CHF 2,4-difluorophenyl cyclopropyl 413.4388 414.30 449 CH CHF 4-fluorophenyl cyclopropyl 395.4483 396.30 450 CH CF—(CH₃) 2,4-difluorophenyl cyclopropyl TFA 451 CH C(O) morphiolin-4-yl cyclopropyl TFA 452 CH CH₂ 2,4-difluorophenyl cyclopropyl TFA 396.4364 397.2 453 CH CHF 5-chloro-2- cyclopropyl 429.8934 430.25 fluorophenyl 454 CH CHF 2,5-difluorophenyl cyclopropyl 7-CH₃ 427.4654 428.30 455 CH C(O) 3- cyclopropyl TFA methoxyazetidin- 1-yl 456 CH C(O) 4- cyclopropyl TFA methylpiperazin- 1-yl 457 CH C(O) pyrrolidin-1-yl cyclopropyl TFA 458 CH C(O) piperidin-1-yl cyclopropyl TFA 459 CH NH 2,4-difluorophenyl cyclopropyl TFA 396.4364 397.3 460 CH C(CH₃)F 5-chloro-2- cyclopropyl 443.92 444.20 fluorophenyl 461 CH CHF 2,5-difluorophenyl cyclopropyl 413.4388 414.20 464 CH CH₂ 2,4-difluorophenyl cyclopropyl 7-Br TFA 474.3444 474.2/ 476.2 465 CH (S)—CHF 2,5-difluorophenyl cyclopropyl 7-CH₃ 427.4654 428.3 468 CH O 4-chloro-2- cyclopropyl 7-CH₃ TFA 427.9023 428.20 fluorophenyl 474 CH CH₂

cyclopropyl 7-CH₃ TF 408.4719 409.3 476 CH H₂ 2,4-difluorophenyl cyclopropyl 7-CN 420.4578 421.25 477 CH O 2,4-difluorophenyl cyclopropyl 7-Cl TFA 431.8662 432.2 478 CH (R)—CHF 2,5-difluorophenyl cyclopropyl 7-CH₃ HCl 427.4654 427.9 484 CH CH₂ 2,4-difluorophenyl cyclopropyl 7-OCH₃ TFA 425.4743 426.3 487 CH CHF 2,5-difluorophenyl cyclopropyl 8-Cl TFA 447.8839 448.2 489 CH CHF 2,4-difluorophenyl cyclopropyl 7-CH₃ TFA 427.4654 428.30 490 CH CHF 2,4-difluorophenyl cyclopropyl 7-Cl TFA 447.8839 448.2 491 CH CH₂ 2,4-difluorophenyl cyclopropyl 7-OH TFA 411.4477 412.3 493 CH CHF 2,4-difluorophenyl cyclopropyl 5-CH₃ TFA 427.4654 428.30 494 CH CH₂ 2,4-difluorophenyl cyclopropyl 5-CH₃ TFA 409.4749 410.30 495 CH O 2,4-difluorophenyl cyclopropyl 5-CH₃ TFA 411.4477 412.30 498 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 7-CH₃ TFA 427.4654 428.30 503 CH (S)—CHF 2,4-difluorophenyl cyclopropyl 7-CH₃ TFA 427.4654 428.30 516 CH CHF 2,4-difluorophenyl cyclopropyl 7-Br TFA 492.3348 492.2/ 494.2 517 CH (S)—CHF 2,4-difluorophenyl cyclopropyl 5-CH₃ TFA 427.4654 428.3 518 CH (S)—CHF 2,4-difluorophenyl cyclopropyl TFA 413.4388 414.3 520 CH CH₂ 2,4-difluorophenyl 2- TFA 413.4636 414.3 methoxyethyl, 521 CH CHF 2,4-difluorophenyl 2- TFA 431.4541 432.2 methoxyethyl, 524 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 7-Cl TFA 447.8839 448.2 525 CH (S)—CHF 2,4-difluorophenyl cyclopropyl 7-Cl TFA 447.8839 448.2 526 CH O 2,4-difluorophenyl 2- TFA 415.4364 416.3 methoxyethyl 528 CH CH₂

cyclopropyl 5-CH₃ 408.4719 409.3 529 CH CH₂

cyclopropyl 5-CH₃ 424.9265 425.2 531 CH CH₃

cyclopropyl 394.4453 395.3 532 CH CH₂

cyclopropyl 5-CH₃ 408.4719 409.3 533 CH CH₂

cyclopropyl 410.8999 411.2 535 CH CF₂ 5-chloro-2- cyclopropyl 7-CH₃ 461.9104 462.2 fluorophenyl 537 CH CF₂ 5-chloro-2- cyclopropyl 5-CH₃ 461.9104 462.2 fluorophenyl 538 CH CH₂

cyclopropyl 5-CH₃ 424.9265 425.2 539 CH CH₂

cyclopropyl 7-CH₃ 424.9265 425.3 540 CH CF₂ 5-chloro-2- cyclopropyl 447.8839 448.2 fluorophenyl 541 CH CF₂ 2,5-difluorophenyl cyclopropyl 431.4293 432.2 542 CH CF₂ 2,5-difluorophenyl cyclopropyl 7-CH₃ 445.4558 446.3 543 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 7-CH₃ 544 CH CF₂ 2,4-difluorophenyl cyclopropyl 5-CH₃ 445.4558 446.2 545 CH CF₂ 2,5-difluorophenyl cyclopropyl 5-CH₃ 445.4558 446.3 547 CH CF₂ 2,4-difluorophenyl cyclopropyl 431.4293 432.2 549 CH (S)—CHF 2,4-difluorophenyl cyclopropyl 7-CN 438.178 439.3 550 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 7-CN 438.178 439.2 553 CH O pyridin-3-yl cyclopropyl 362.1855 363.2 554 CH O 4-methoxyphenyl cyclopropyl 391.2008 392.3 555 CH O pyridin-2-yl cyclopropyl 362.1855 363.2 556 CH O pyridin-4-yl cyclopropyl 362.1855 363.2 557 CH C(O) 2-methoxyphenyl cyclopropyl TFA 403.2008 404.3 558 CH O 4-cyanophenyl cyclopropyl 386.1855 387.2 559 CH C(O) 2-chlorophenyl cyclopropyl TFA 407.1513 408.2 560 CH O 3-methoxyphenyl cyclopropyl TFA 391.2008 392.3 561 CH O 2-methoxyphenyl cyclopropyl TFA 391.2008 392.3 562 CH C(O) phenyl cyclopropyl 373.1903 374.2 563 CH C(O) 2,3-difluorophenyl cyclopropyl TFA 409.1714 410.2 564 CH C(O) 3-chlorophenyl cyclopropyl 407.1513 408.2 565 CH O 3-cyanophenyl cyclopropyl 386.1855 387.3 566 CH C(O) 3-methoxyphenyl cyclopropyl 403.2008 404.3 567 CH C(O) 2-mehylphenyl cyclopropyl TFA 387.2059 388.3 568 CH C(O) 2,6-difluorophenyl cyclopropyl TFA 409.1714 410.3 569 CH C(O) 2-chloro-5- cyclopropyl TFA 425.1419 426.2 fluorophenyl 570 CH C(O) 3-fluorophenyl cyclopropyl TFA 391.1808 392.3 571 CH C(O) 2,3-difluoro-6- cyclopropyl TFA 443.877 444.2 chlorophenyl 572 CH C(O) 2-fluoro-4- cyclopropyl TFA 409.457 410.2 methoxyphenyl 573 CH C(O) 3-fluoro-2- cyclopropyl HCl 425.886 426.2 chlorophenyl 574 CH C(O) 5-chlorothien-3-yl cyclopropyl HCl 413.924 414.2 575 CH C(O) thien-2-yl cyclopropyl TFA 379.479 380.2 576 CH O 2-cyanophenyl cyclopropyl 386.449 387.2 577 CH C(O) 2-fluoro-6- cyclopropyl 425.886 426.2 chlorophenyl 578 CH C(O) 3-cyanophenyl cyclopropyl TFA 398.460 399.3 579 CH (S)—CHF 2,4-difluorophenyl cyclopropyl 7- TFA 484.540 485.3 C(O)N(CH₃)₂ 580 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 7- TFA 484.540 485.3 C(O)N(CH₃)₂ 581 CH (S)—CHF 2,4-difluorophenyl cyclopropyl 5- TFA 526.5734 527.3 C(O)morpholin- 4-yl 582 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 5- TFA 526.5734 527.3 C(O)morpholin- 4-yl 583 CH C(O) 2- cyclopropyl TFA 419.543 420.3 thiomethoxyphenyl 584 CH O 4-(1- cyclopropyl TFA 403.497 404.2 oxoethyl)phenyl 585 CH O 4-(1- cyclopropyl TFA 405.5128 406.3 hydroxyethyl)phenyl 586 CH C(O) thien-3-yl cyclopropyl TFA 379.479 380.2 587 CH C(O) 2-bromophenyl cyclopropyl TFA 451.367 452.1 588 CH C(O) 2-bromopyrid-3-yl cyclopropyl TFA 453.355 453.2/ 455.2 589 CH C(O) 2-fluoro-5- cyclopropyl TFA 416.451 417.3 cyanophenyl 590 CH O 4-(N,N- cyclopropyl TFA 432.554 433.3 dimethylamide)phenyl 591 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 7- TFA 496.527 497.3 C(O)azetidin- 1-yl 592 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 7-C(O)(4- 514.5178 515.3 fluoroazetidin- 1-yl 593 CH (S)—CHF 2,4-difluorophenyl cyclopropyl 7- TFA 496.527 497.3 C(O)azetidin- 1-yl 594 CH CH₂ 2,4-difluorophenyl cyclopropyl 7-Cl 429.893 430.3 595 CH C(O) 6-fluoro-3- cyclopropyl TFA 437.553 438.3 thiomethyoxyphenyl 597 CH C(O) 6-chloro-3- cyclopropyl 7-Cl 467.3505 467.2 cyanophenyl 598 CH C(O) 2-(N,N- cyclopropyl 7- 540.616 541.3 dimethylamide)-5- C(O)N(CH₃)₂ cyanophenyl 599 CH O 2,4-difluorophenyl cyclopropyl 7- 468.499 469.3 C(O)N(CH₃)₂ 602 CH O 4- cyclopropyl TFA 407.552 408.3 thiomethyoxyphenyl 603 CH O 4-ethyoxyphenyl cyclopropyl TFA 405.513 406.3 604 CH C(O) 6-fluoro-3- cyclopropyl 7-C(O)(4- TFA 495.346 495.2/ cyanophenyl methylpiperazin 497.2 1-yl) 606 CH O 2-fluoro-4- cyclopropyl 5- 480.555 481.4 methoxyphenyl C(O)N(CH₃)₂ 607 CH C(O) 2-fluoro-4- cyclopropyl 5-CN TFA 434.489 435.3 methoxyphenyl 608 CH C(O) 2-fluoro-4- cyclopropyl 5- TFA 494.581 495.4 methoxyphenyl (morpholin- 4-yl) 610 N C(O) 3-fluoro-6- cyclopropyl 7- 497.952 498.3 chlorophenyl C(O)N(CH₃)₂ 612 CH O 2-fluoro-4- cyclopropyl 5- TFA 522.591 523.4 methoxyphenyl (morpholin- 4-yl) 613 N CH₂ 2-fluoro-4- cyclopropyl 7- TFA 509.570 510.4 methoxyphenyl (morpholin- 4-yl) 614 N CH₂ 2,4-difluorophenyl cyclopropyl 5-CN TFA 421.465 422.3 615 N CH₂ 2-fluoro-4- cyclopropyl 5-CN TFA 433.501 434.4 methoxyphenyl 616 N CH₂ 2-fluoro-4- cyclopropyl 7- TFA 479.569 480.4 methoxyphenyl C(O)N(CH₃)₂ 631 CH O 2-fluoro-4- isopropyl 7- TFA 486.989 487.3 chlorophenyl C(O)N(CH₃)₂ 632 CH C(O) 3,5-difluorophenyl isopropyl 7-CN TFA 436.478 437.3 635 N CH₂ 2,4-difluorophenyl isopropyl 7- TFA 469.551 470.4 C(O)N(CH₃)₂ 636 CH C(O) 3,5-difluorophenyl isopropyl 7- TFA 482.545 483.4 C(O)N(CH₃)₂ 637 CH CH₂ 2-fluoro-4- isopropyl 7-CN TFA 434.529 435.4 methoxyphenyl 646 CH O 2,4-difluorophenyl tert-butyl 7-CN 438.473 439.4 647 CH O 2-fluoro-4- isopropyl TFA 398.434 493.8 hydroxyphenyl 648 CH O 2,4-difluorophenyl 2,2- 7- TFA 492.469 493.8 difluoroethyl C(O)N(CH₃)₂ 653 CH SO₂ 4-fluorophenyl cyclopropyl 7-CH₃ TFA 441.522 442.9

291 N CH₂ 2,5-difluorophenyl cyclopropyl TFA 396.4364 397.3 292 N CH₂ 2,5-dichlorophenyl cyclopropyl TFA 429.3456 429.2 303 N C(O) 4-chlorophenyl cyclopropyl TFA 408.884 409.3 309 N SO₂ 4-fluorophenyl cyclopropyl TFA 428.4832 429.2 355 N CH₂ 2,4,5- cyclopropyl TFA 414.4268 415.3 trifluorophenyl 356 N CH₂ 2,4-difluorophenyl cyclopropyl TFA 396.4364 397.3 363 N CH₂ 2,4-difluorophenyl 2,2- TFA 420.4066 421.2 difluoroethyl 364 N CH_(2`) 2,4,5- 2,2 TFA 438.3971 439.2 trifluorophenyl difluoroethyl 369 N CH₂ 2,4,5- pyridin-3-yl TFA 451.447 452.3 trifluorophenyl 390 N CH₂ 2,5-difluorophenyl pyridin-3-yl 6-CN TFA 433.4565 434.25 397 N CH₂ 2,4-difluorophenyl cyclopropyl 6-Br TFA 475.3325 475.2/ 477.2 398 N CH₂ 2,4-difluorophenyl cyclopropyl 6-CN TFA 421.4458 422.25 426 CH CH₂ 2,4-difluorophenyl cyclopropyl TFA 395.4483 396.3 427 CH CH₂ 2,4-difluorophenyl 2,2- 419.4185 320.3 difluoroethyl 439 CH CH₂ 2,4-difluorophenyl cyclopropyl 6-CH₃ TFA 409.4749 410.3 551 CH (S)—CHF 2,4-difluorophenyl cyclopropyl 6-CN 438.178 439.2 552 CH (R)—CHF 2,4-difluorophenyl cyclopropyl 6-CN 438.178 439.2 611 CH O 2-fluoro-4- cyclopropyl TFA 409.477 410.3 methoxyphenyl 617 CH O 2-fluoro-4- cyclopropyl TFA 395.450 396.3 hydroxyphenyl 618 CH O 2-fluoro-4- isopropyl TFA 411.473 412.3 methoxyphenyl 621 CH O 2,4-difluorophenyl isopropyl TFA 399.457 400.3 622 CH CHF 2,4-difluorophenyl isopropyl TFA 415.474 416.3 623 CH O 2-fluoro-4- ethyl TFA 397.466 398.3 methoxyphenyl 655 CH O 2,4-difluorophenyl isopropyl 399.437 400.0 656 CH O 2,4-difluorophenyl cyclobutyl 411.448 412.0

 2 N CH₂ 3-methylphenyl cyclopropyl TFA 374.482 375.3  22 N CH₂ 3-chlorophenyl phenyl TFA 430.9326 431.25 44 N CH₂ 2,5-dichlorophenyl cyclopropyl TFA 429.3456 429.2

392 N CH₂ 2,4-difluorophenyl cyclopropyl TFA 397.4244 398.25 452 CH CH₂ 2,4-difluorophenyl cyclopropyl TFA 396.4364 397.2 596 CH (S)—CHF 2,4-difluorophenyl cyclopropyl TFA 414.455 415.3 600 CH O 2-fluoro-4- cyclopropyl TFA 410.469 411.3 methoxyphenyl 601 CH (R)—CHF 2,4-difluorophenyl cyclopropyl TFA 414.455 415.3 605 CH O 2-fluoro-4- cyclopropyl 535.633 536.4 methoxyphenyl 619 CH O 2-fluoro-4- cyclopropyl TFA 426.530 427.3 thiomethoxyphenyl 620 CH O 2,4-difluorophenyl cyclopropyl TFA 398.429 399.3 624 CH O 2-fluoro-4- cyclopropyl TFA 396.418 397.3 hydroxyphenyl 625 CH O 2-fluoro-4- isopropyl TFA 412.848 413.4 methoxyphenyl 626 CH O 2-fluoro-4- cyclopropyl TFA 404.460 405.3 cyanophenyl 633 CH O 2,4-difluorophenyl isopropyl TFA 400.445 401.3 634 CH CHF 2,4-difluorophenyl isopropyl TFA 416.462 417.3 638 CH O 2-fluoro-4- (S)-sec- TFA 426.507 427.0 methoxyphenyl butyl 639 CH O 2-fluoro-4- (R)-sec- TFA 426.507 427.0 methoxyphenyl butyl 640 CH O 2-fluoro-4- isopropyl TFA 406.464 407.9 cyanophenyl 641 CH (R)—CHF 2,4-difluorophenyl isopropyl TFA 415.463 416.9 642 CH C(O) 2-fluoro-4- isopropyl TFA 424.491 425.0 methoxyphenyl 643 CH CH₂ 2-fluoro-4- isopropyl TFA 410.508 411.0 methoxyphenyl 644 CH O 2-fluoro-4- isopropyl TFA 415.899 416.9 chlorophenyl 645 CH (R)—CHF 2,4-difluorophenyl 2- TFA 428.473 429.0 methylcyclopropyl 647 CH O 2-fluoro-4- isopropyl TFA 398.434 493.8 hydroxyphenyl 649 N CH₂ 3-methoxyphenyl isopropyl TFA 399.440 400.0 650 CH O 3-methoxyphenyl isopropyl TFA 397.470 395.0 651 CH O 2,4-difluorophenyl isopropyl 5-CH₃ TFA 428.478 428.9 7-CH₃ 652 CH O 2,4-difluorophenyl isopropyl 7-CH₃ TFA 414.452 415.0 654 CH O 2-fluoro-4- cyclopropyl TFA 414.864 414.9 chlorophenyl 657 CH O 2-fluoro-4- isopropyl TFA 430.451 430.9 fluoromethoxyphenyl and are named as

N-cyclopropyl-3-(4-(3-methylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-2-(4-(3-methylbenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(3-methylbenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazin-2-amine (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3-(trifluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-(methylsulfonyl)phenyl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,5-dichlorophenyl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3,4-dichlorophenyl)methanone, 2,2,2- trifluoroacetic acid salt (3-chloro-4-methoxyphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3,5-dichlorophenyl)methanone, 2,2,2- trifluoroacetic acid salt (3-chlorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-chlorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(pyridin-3-ylmethyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,3-dichlorophenyl)methanone, 2,2,2- trifluoroacetic acid salt (2-chlorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(m-tolyl)methanone, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(pyridin-4-ylmethyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(3-(trifluoromethyl)benzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chlorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(pyridin-2-ylmethyl)piperazin-1-yl)quinoxalin-2-amine, 22,2,2-trifluoroacetic acid salt N-(4-bromophenyl)-3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 2-(4-(3-chlorobenzyl)piperazin-1-yl)-N-phenylpyrido[2,3-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-phenylpyrido[2,3-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-phenylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(4-(trifluoromethoxy)phenyl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(4-propylphenyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-(trifluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt 3-(4-(2-chlorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(4-(methylsulfonyl)benzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(p-tolyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(4-methoxyphenyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(2-methoxyphenyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(4-(trifluoromethyl)benzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(3-methoxyphenyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-(4-(tert-butyl)phenyl)-3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(4-isopropoxyphenyl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(4-fluorophenyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopentylamino)quinoxalin-2-yl)piperazin-1-yl)(2,5-dichlorophenyl)methanone, 2,2,2- trifluoroacetic acid salt N-cyclopentyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt (2,5-dichlorophenyl)(4-(3-(phenylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt N-(cyclopropylmethyl)-3-(4-(2,5-dichlorobenzyl)piperazin-l-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-phenylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-2-(4-(2,5-dichlorobenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt 7-bromo-N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 6-bromo-N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt mixture of N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-7-methoxyquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt and N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-7-methoxyquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,3-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,6-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-(3-bromophenyl)-3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-(2-bromophenyl)-3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,5-dichlorothiophen-3-yl)methanone mixture of N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-7-fluoroquinoxalin-2-amine and N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-7-fluoroquinoxalin-2-amine 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(3-methoxyphenyl)quinoxalin-2-amine 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(4-methoxyphenyl)quinoxalin-2-amine 4-((3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-yl)amino)benzonitrile 2-(cyclopropylamino)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2-methoxyphenyl)quinoxalin-2-amine 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(4-fluorophenyl)quinoxalin-2-amine N-cyclopropyl-3-(4-(1-(2,5-dichlorophenyl)ethyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazin-2-amine N-(4-bromophenyl)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine 3-(4-(3-bromobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(3-methoxypropyl)quinoxalin-2-amine (2-chloro-4-(methylsulfonyl)phenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1- yl)methanone (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3,6-dichloropyridin-2-yl)methanone benzofuran-3-yl(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(pyridin-4-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-(3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-yl)-1,3,4-thiadiazol-2-amine, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3,4-dimethylphenyl)methanone, 2,2,2- trifluoroacetic acid salt 2,2,2-trifluoroacetic acid, N-cyclopropyl-3-(4-(3,4-dimethylbenzyl)piperazin-1-yl)quinoxalin-2-amine salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,4-dichlorophenyl)methanone, 2,2,2- trifluoroacetic acid salt 4-(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazine-1-carbonyl)benzonitrile, 2,2,2-trifluoroacetic acid salt 4-((4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methyl)benzonitrile, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-ethylphenyl)methanone, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(4-ethylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(3,4-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,5-difluorophenyl)methanone, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(naphthalen-2-yl)methanone, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(naphthalen-2-ylmethyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt (4-(tert-butyl)phenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (2-bromo-5-methoxyphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt (3-bromo-4-methoxyphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt (4-bromo-2-chlorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(5-fluoro-2-methylphenyl)methanone, 2,2,2- trifluoroacetic acid salt (3-bromo-4-fluorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-bromo-2-fluorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (5-bromo-2-fluorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-ethoxyphenyl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3-isopropylphenyl)methanone, 2,2,2- trifluoroacetic acid salt 3-(4-(4-bromobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-((4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methyl)benzonitrile, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(4-fluorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(4-isopropylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(5-methylisoxazol-3-yl)methanone N-cyclopropyl-3-(4-((2,5-dichlorothiophen-3-yl)methyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(benzofuran-3-ylmethyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine N-cyclopropyl-3-(4-((3,6-dichloropyridin-2-yl)methyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt cyclohexyl(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-5,7-dimethylquinoxalin-2-amine N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-6,8-dimethylquinoxalin-2-amine N-cyclopropyl-3-(4-(phenylsulfonyl)piperazin-1-yl)quinoxalin-2-amine N-cyclopropyl-3-(4-phenethylpiperazin-1-yl)quinoxalin-2-amine 3-(4-(4-chlorophenethyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine N-cyclopropyl-3-(4-(4-methoxyphenethyl)piperazin-1-yl)quinoxalin-2-amine 3-(4-(cyclohexylmethyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-isobutylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-isopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2-ethylbutyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(4-methylpentan-2-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-neopentylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-isopentylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-(sec-butyl)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-propylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2-methoxyethyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclobutyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 5-bromo-N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-isopropylphenyl)methanone, 2,2,2- trifluoroacetic acid salt (4-bromo-2-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (2-chloro-3,6-difluorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-((4-(trifluoromethoxy)phenyl)sulfonyl)piperazin-1-yl)quinoxalin-2-amine N-(3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-yl)thiazol-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(pyrimidin-2-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(pyrimidin-5-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(cyclopentylsulfonyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine N-cyclopropyl-3-(4-(5-fluoro-2-methylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt (2-chloro-5-iodophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (5-bromo-2-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-(trifluoromethoxy)phenyl)methanone, 2,2,2-trifluoroacetic acid salt 8-bromo-N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 8-bromo-N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(1H-indol-6-yl)methanone, 2,2,2- trifluoroacetic acid salt (5-chloro-2-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-chloro-2-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,4-dimethylphenyl)methanone, 2,2,2- trifluoroacetic acid salt (2-chloro-5-methoxyphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt 5-(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazine-1-carbonyl)-2-isopropoxybenzonitrile, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2-methoxy-5- (trifluoromethoxy)phenyl)methanone, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,3,5-trichlorophenyl)methanone, 2,2,2- trifluoroacetic acid salt (2-chloro-6-(trifluoromethyl)phenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,5-dichlorophenethyl)piperazin-1-yl)quinoxalin-2-amine 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)quinoxalin-2-amine (4-(chloromethyl)phenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(1H-indol-5-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-bromo-3-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt 3-(4-(2-chloro-4-(methylsulfonyl)benzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)pyrido[2,3-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(cyclopropylamino)-2-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-fluoro-3-methoxyphenyl)methanone, 2,2,2-trifluoroacetic acid salt (3-bromo-4-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-chloro-3-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-fluoro-2-methylphenyl)methanone N-cyclopropyl-3-(4-(4-fluoro-2-methylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-((5-methylisoxazol-3-yl)methyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 2-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-3-(pyridin-3-ylamino)quinoxaline-6-carbonitrile 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile (4-chlorophenyl)(4-(3-(cyclopropylamino)-7-fluoroquinoxalin-2-yl)piperazin-1-yl)methanone 2-(cyclopropylamino)-3-(4-(phenylsulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile 3-(4-(phenylsulfonyl)piperazin-1-yl)-N-(pyridin-3-yl)quinoxalin-2-amine 3-(4-(3-chlorobenzyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile N-(tert-butyl)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(3,3-dimethylbutyl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2-ethoxyethyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2-isopropoxyethyl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(3-ethoxypropyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclohexyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(tetrahydro-2H-pyran-4-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt (R)-2-((3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-yl)amino)propan-1-ol, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyrazin-2-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyrimidin-4-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyridazin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt mixture of 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-6-fluoro-N-(pyridin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt and 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-7-fluoro-N-(pyridin-3-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(1,2,4-triazin-3-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(5,6-dimethyl-1,2,4-triazin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-(3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-yl)-3,4-dimethylisoxazol-5-amine, 2,2,2- trifluoroacetic acid salt (3-bromo-2-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3,5-difluorophenyl)methanone, 2,2,2- trifluoroacetic acid salt (4-bromophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt 3-(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazine-1-carbonyl)benzonitrile, 2,2,2-trifluoroacetic acid salt (3-bromophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,6-dichlorophenyl)methanone, 2,2,2- trifluoroacetic acid salt (2-bromo-4-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt 4-(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazine-1-carbonyl)-3-fluorobenzonitrile, 2,2,2- trifluoroacetic acid salt benzo[d][1,2,3]thiadiazol-5-yl(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt (2-chloro-5-fluorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,6-difluoro-3-methylphenyl)methanone, 2,2,2-trifluoroacetic acid salt (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2-methoxy-5- (trifluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt (4-bromo-3-(trifluoromethyl)phenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1- yl)methanone N-cyclopropyl-3-(4-(3,5-difluorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(4-chloro-3-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,3-dimethylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2-bromo-5-methoxybenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(3-bromo-4-methoxybenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(4-bromo-2-chlorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(3-bromo-4-fluorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(4-bromo-2-fluorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(5-bromo-2-fluorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(5-bromo-2-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-((1H-indol-6-yl)methyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(5-chloro-2-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chloro-2-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2-chloro-3,6-difluorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-dimethylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2-chloro-5-methoxybenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2-chloro-5-fluorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2-chloro-6-(trifluoromethyl)benzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(3-isopropylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-6-fluoro-3-(4-(phenylsulfonyl)piperazin-1-yl)quinoxalin-2-amine N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-6-fluoroquinoxalin-2-amine 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyridin-4-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-6,7-difluoroquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(3-chloro-4-methoxybenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(4-bromo-3-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(4-bromo-2-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2-chloro-5-iodobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2 -trifluoroacetic acid salt N-cyclopropyl-3-(4-(2-methoxy-5-(trifluoromethoxy)benzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,3,5-trichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-((2-chloro-5-fluoropyridin-3-yl)methyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt (4-chlorophenyl)(4-(3-(pyridin-3-ylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt 3-(4-((3-chlorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile 3-(4-((3-chlorophenyl)sulfonyl)piperazin-1-yl)-N-cyclopropyl-6-fluoroquinoxalin-2-amine 2-(cyclopropylamino)-3-(4-((2,5-dichlorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile 3-(4-((4-chlorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyridin-2-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt (4-chloro-3-methylphenyl)(4-(3-(pyridin-3-ylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-6,7-difluoroquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt (3-bromo-4-fluorophenyl)(4-(3-(cyclopropylamino)-6,7-difluoroquinoxalin-2-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt 3-(4-(2-bromo-5-chlorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(5-chloro-2-(trifluoromethyl)benzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,6-difluoro-3-methylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2-methoxy-5-(trifluoromethyl)benzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(o-tolylsulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile 2-(cyclopropylamino)-3-(4-((3-fluorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(m-tolylsulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile 2-(cyclopropylamino)-3-(4-tosylpiperazin-1-yl)quinoxaline-6-carbonitrile 2-(cyclopropylamino)-3-(4-((2-fluorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline-5-carbonitrile, 2,2,2- trifluoroacetic acid salt (4-chlorophenyl)(4-(3-(cyclopropylamino)-6,7-difluoroquinoxalin-2-yl)piperazin-1-yl)methanone 3-(4-((2-chlorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((4-fluorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-cyclopropyl-6,7-difluoroquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt (4-bromo-3-fluorophenyl)(4-(3-(cyclopropylamino)-7-fluoroquinoxalin-2-yl)piperazin-1- yl)methanone 3-(cyclopropylamino)-2-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline-5-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-((2-bromophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile 3-(4-((3-bromophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile 3-(4-((4-bromophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile 3-(4-((2-cyanophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-((3-cyanophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-((4-cyanophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(4-fluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile 3-(4-(3-bromo-4-fluorobenzoyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(3-bromo-4-fluorobenzoyl)piperazin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 2-(cyclobutylamino)-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(3-bromo-4-fluorobenzoyl)piperazin-1-yl)-2-(cyclobutylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt (4-chlorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,5-dichloroisonicotinoyl)piperazin-1-yl)quinoxaline-6-carbonitrile 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-(cyclobutylamino)quinoxaline-6-carbonitrile 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(4- (trifluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2,2,2-trifluoroethyl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((3,5-dimethylisoxazol-4-yl)sulfonyl)piperazin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((2,5-dimethylphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((4-methoxyphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((2-methoxyphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((3-methoxyphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((5-chlorothiophen-2-yl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(mesitylsulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((2-methoxy-4-methylphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((5-chloro-1,3-dimethyl-1H-pyrazol-4-yl)sulfonyl)piperazin-1-yl)-2- (cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((2,3,4-trifluorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((4-(tert-butyl)phenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((4-chloro-2,5-dimethylphenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((3-chloro-5-fluoro-2-methylphenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline- 6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((4-(trifluoromethoxy)phenyl)sulfonyl)piperazin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((5-bromothiophen-2-yl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((4-bromo-2-fluorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((2-chloro-5-(trifluoromethyl)phenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline- 6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((4-bromo-2-chlorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-((4-fluorophenyl)sulfonyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(4- (difluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt 3-(4-(5-chloro-2-(difluoromethoxy)benzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2- amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(4-fluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-2-(4-(2,5-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-2-(4-(2,5-dichlorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,6-dichlorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(3-chlorobenzoyl)piperazin-1-yl)-2-((cyclobutylmethyl)amino)quinoxaline-6-carbonitrile 2-((cyclobutylmethyl)amino)-3-(4-(2,5-dichlorobenzoyl)piperazin-1-yl)quinoxaline-6-carbonitrile 2-(cyclopropylamino)-3-(4-(2,5-dichloronicotinoyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-(oxetan-3-ylamino)quinoxaline-6-carbonitrile N-cyclopropyl-3-(4-(2,6-dichlorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-(oxetan-3-ylamino)quinoxaline-6-carbonitrile 3-(4-(5-chloro-2-propoxybenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-((4-(trifluoromethyl)phenyl)sulfonyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2- amine, 2,2,2-trifluoroacetic acid salt 2-(4-(4-chlorobenzoyl)piperazin-1-yl)-3-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt (4-chlorophenyl)(4-(3-(cyclopropylamino)pyrido[3,4-b]pyrazin-2-yl)piperazin-1-yl)methanone, 2,2,2- trifluoroacetic acid salt 3-(cyclopropylamino)-2-(4-(2,5-difluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(5-(tert-butyl)-2-methoxybenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,5-dimethylbenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(cyclopropylamino)-2-(4-((4-fluorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-2-(4-((4-fluorophenyl)sulfonyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile N-cyclopropyl-3-(4-(2,6-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((6-oxo-1,6-dihydropyridin-3-yl)amino)quinoxaline-6- carbonitrile 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-((6-oxo-1,6-dihydropyridin-3-yl)amino)quinoxaline-6- carbonitrile 3-(4-(3-chloro-4-fluorobenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chloro-3-fluorobenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(3,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((6-oxo-1,6-dihydropyridin-4-yl)amino)quinoxaline-6- carbonitrile 2-(cyclopropylamino)-3-(4-((4-ethylphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((6-oxo-1,6-dihydropyridin-2-yl)amino)quinoxaline-6- carbonitrile 2-(cyclopropylamino)-3-(4-((2-fluoro-5-methylphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-((6-oxo-1,6-dihydropyridin-2-yl)amino)quinoxaline-6- carbonitrile 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((6-oxo-1,6-dihydropyridin-2-yl)amino)quinoxaline-6- carbonitrile 2-(cyclopropylamino)-3-(4-((3,4-difluorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-((2-oxo-1,2-dihydropyridin-3-yl)amino)quinoxaline-6- carbonitrile 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile 2-(cyclopropylamino)-3-(4-((2,5-dimethoxyphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((2-chloro-4-(trifluoromethyl)phenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline- 6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2-chloro-5-fluorobenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((6-methoxypyridin-3-yl)amino)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-((3-oxocyclobutyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((3-oxocyclobutyl)amino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 2-(cyclobutylamino)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-((2-fluoroethyl)amino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-(isoxazol-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-(isoxazol-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-((3-cyano-4-fluorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-((5-chloro-2-methoxyphenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((5-chloro-2,4-difluorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((5-bromo-6-chloropyridin-3-yl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((4-bromo-2,5-difluorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-((2-fluoroethyl)amino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((2-fluoroethyl)amino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 8-chloro-3-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt 8-chloro-N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 8-chloro-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 8-chloro-N-cyclopropyl-3-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-2-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-2-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((2,4-dimethoxyphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile (4-chloro-3-fluorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(3,4-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt (3-chloro-4-fluorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt (4-chloro-2-fluorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt (2-chloro-4-fluorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt 2-(4-(2,4-difluorobenzyl)piperazin-1-yl)-N-(2,2-difluoroethyl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt N-(2,2-difluoroethyl)-2-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-N-(2,2-difluoroethyl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-N-(2,2-difluoroethyl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt (4-chloro-2-fluorophenyl)(4-(2-((2,2-difluoroethyl)amino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt N-(pyridin-3-yl)-2-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt N-(2,2-difluoroethyl)-3-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt (4-chloro-2-hydroxyphenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt 3-(cyclopropylamino)-2-(4-(2,4-difluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 2-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-3-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(cyclopropylamino)-2-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 2-(pyridin-3-ylamino)-3-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chloro-2-fluorobenzoyl)piperazin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-(isoxazol-3-ylamino)quinoxaline-6-carbonitrile 2-(4-(2,4-difluorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)pyrido[3,4-b]pyrazin-3-amine (4-chloro-2-methoxyphenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(2-fluoro-4- (trifluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt (5-chloro-3-fluoropyridin-2-yl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(2-fluoro-4- methylphenyl)methanone, 2,2,2-trifluoroacetic acid salt (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(2-fluoro-4- methoxyphenyl)methanone, 2,2,2-trifluoroacetic acid salt (4-chloro-2-methylphenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt 4-(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazine-1-carbonyl)-3-fluorobenzonitrile, 2,2,2-trifluoroacetic acid salt (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(4-fluoro-2- hydroxyphenyl)methanone, 2,2,2-trifluoroacetic acid salt (4-chloro-2,6-difluorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(3-fluoropyridin-2-yl)methanone, 2,2,2-trifluoroacetic acid salt 2-(4-(2,5-difluorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt (4-chloro-2-(trifluoromethyl)phenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1- yl)methanone, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2- trifluoroacetic acid salt (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(2,4,6-trifluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(2,4-difluoro-6- hydroxyphenyl)methanone, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-N-cyclopropyl-7-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt 7-bromo-3-(cyclopropylmethyl)-2-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazine 2,2,2- trifluoroacetate 3-(cyclopropylamino)-2-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((3,3,3-trifluoropropyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-2-((3,3,3-trifluoropropyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 6-bromo-N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 6-bromo-3-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 6-bromo-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile 7-bromo-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-N-(2-methoxyethyl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-2-((2-methoxyethyl)amino)quinoxaline-6-carbonitrile N-cyclopropyl-3-(4-((5-methyloxazol-2-yl)methyl)piperidin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-((3-methyl-1,2,4-oxadiazol-5-yl)methyl)piperidin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-benzylpiperidin-1-yl)-N-phenylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-phenoxypiperidin-1-yl)quinoxalin-2-amine 3-(4-((4-chlorophenyl)amino)piperidin-1-yl)-N-cyclopropylquinoxalin-2-amine, 22,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(2-chlorophenoxy)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2-fluorophenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(3-fluorophenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(4-fluorophenyl)methanone, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(4-fluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(3,4-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-((4-fluorophenyl)sulfonyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chlorobenzyl)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chlorophenoxy)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(3-chlorophenoxy)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-2-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt 2-(4-(2,4-difluorobenzyl)piperidin-1-yl)-N-(2,2-difluoroethyl)pyrido[3,4-b]pyrazin-3-amine N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt (4-chlorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,5-difluorophenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4,6-trifluorophenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(4-fluorophenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2-fluorophenyl)methanone, 2,2,2- trifluoroacetic acid salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,5-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt 3-(4-(5-chloro-2-fluorophenoxy)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-phenoxypiperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,4-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-2-(4-(2,4-difluorobenzyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt (1-(2-(cyclopropylamino)-7-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,5- difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,4,6-trifluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt (4-chloro-2,6-difluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4- yl)methanone, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt (4-chloro-2-fluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4- yl)methanone, 2,2,2-trifluoroacetic acid salt (5-chloro-2-fluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4- yl)methanone, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine N-cyclopropyl-3-(4-(fluoro(4-fluorophenyl)methyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-((5-chloro-2-fluorophenyl)fluoromethyl)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2- amine N-cyclopropyl-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin- 2-amine (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(3-methoxyazetidin-1- yl)methanone (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(4-methylpiperazin-1- yl)methanone (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(pyrrolidin-1-yl)methanone (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(piperidin-1-yl)methanone N-cyclopropyl-3-(4-((2,4-difluorophenyl)amino)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 22,2,2- trifluoroacetic acid salt 3-(4-(1-(5-chloro-2-fluorophenyl)-1-fluoroethyl)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin- 2-amine N-cyclopropyl-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile 2-(cyclobutylamino)-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)quinoxaline-6-carbonitrile 7-bromo-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt (S)-N-cyclopropyl-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4- b]pyrazin-2-amine 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-N-cyclopropyl-7-methylpyrido[3,4-b]pyrazin-2- amine, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 3-(4-(5-chloro-2-fluorobenzoyl)piperidin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((4-fluoro-2-oxopyridin-1(2H)-yl)methyl)piperidin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,5-difluorobenzoyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2- trifluoroacetic acid salt 1-((1-(2-(cyclopropylamino)-7-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)-4- fluoropyridin-2(1H)-one, 2,2,2-trifluoroacetic acid salt 2-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-3-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile 7-chloro-N-cyclopropyl-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt (R)-N-cyclopropyl-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4- b]pyrazin-2-amine, hydrogen chloride salt N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-6,7-difluoroquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-6-fluoroquinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclobutylamino)-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-7-methoxypyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(cyclopropylamino)-2-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 8-chloro-N-cyclopropyl-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin- 2-amine, 2,2,2-trifluoroacetic acid salt 3-(cyclopropylamino)-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin- 2-amine, 2,2,2-trifluoroacetic acid salt 7-chloro-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin- 2-amine, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-7-ol, 2,2,2- trifluoroacetic acid salt (R)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-5-methylpyrido[3,4-b]pyrazin- 2-amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-5-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-5-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt 6-bromo-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-2-((3,3,3-trifluoropropyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt (R)-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4- b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-((3,3,3-trifluoropropyl)amino)quinoxaline- 6-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-2-((3,3,3-trifluoropropyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt 6-bromo-N-cyclopropyl-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt 6-bromo-N-cyclopropyl-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)quinoxalin-2-amine, 2,2,2- trifluoroacetic acid salt (S)-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4- b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt (S)-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6- carbonitrile (R)-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6- carbonitrile (S)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile (R)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile (S)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6- carbonitrile (R)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6- carbonitrile (S)-3-(cyclopropylamino)-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile (R)-3-(cyclopropylamino)-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile 2-((2,2-difluoroethyl)amino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile 2-((2,2-difluoroethyl)amino)-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)quinoxaline-6-carbonitrile (S)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile, 2,2,2-trifluoroacetic acid salt 7-bromo-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin- 2-amine, 2,2,2-trifluoroacetic acid salt (S)-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-5-methylpyrido[3,4- b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt (S)-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2- amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-2-((2-methoxyethyl)amino)quinoxaline-6-carbonitrile 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-N-(2-methoxyethyl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N-(2-methoxyethyl)pyrido[3,4-b]pyrazin-2- amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-2-((2-methoxyethyl)amino)quinoxaline-6-carbonitrile 3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-((2-methoxyethyl)amino)quinoxaline-6- carbonitrile (R)-7-chloro-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4- b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt (S)-7-chloro-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4- b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt 3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-N-(2-methoxyethyl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-((4-chloro-2-oxopyridin-1(2H)-yl)methyl)piperidin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile 1-((1-(2-(cyclopropylamino)-5-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)-5- fluoropyridin-2(1H)-one 4-chloro-1-((1-(2-(cyclopropylamino)-5-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4- yl)methyl)pyridin-2(1H)-one 2-(cyclopropylamino)-3-(4-((5-fluoro-2-oxopyridin-1(2H)-yl)methyl)piperidin-1-yl)quinoxaline-6- carbonitrile 1-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)-4-fluoropyridin-2(1H)- one 1-((1-(2-(cyclopropylamino)-5-methylpyrido [3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)-4- fluoropyridin-2(1H)-one 5-chloro-1-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)pyridin-2(1H)- one 3-(4-((5-chloro-2-fluorophenyl)difluoromethyl)piperidin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile 3-(4-((5-chloro-2-fluorophenyl)difluoromethyl)piperidin-1-yl)-N-cyclopropyl-7-methylpyrido[3,4- b]pyrazin-2-amine 3-(4-((5-chloro-2-oxopyridin-1(2H)-yl)methyl)piperidin-1-yl)-2-(cyclopropylamino)quinoxaline-6- carbonitrile 3-(4-((5-chloro-2-fluorophenyl)difluoromethyl)piperidin-1-yl)-N-cyclopropyl-5-methylpyrido[3,4- b]pyrazin-2-amine 5-chloro-1-((1-(2-(cyclopropylamino)-5-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4- yl)methyl)pyridin-2(1H)-one 5-chloro-1-((1-(2-(cyclopropylamino)-7-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4- yl)methyl)pyridin-2(1H)-one 3-(4-((5-chloro-2-fluorophenyl)difluoromethyl)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2- amine N-cyclopropyl-3-(4-((2,5-difluorophenyl)difluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine N-cyclopropyl-3-(4-((2,5-difluorophenyl)difluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4- b]pyrazin-2-amine N-cyclopropyl-3-(4-((2,4-difluorophenyl)difluoromethyl)piperidin-1-yl)-5-methylpyrido[3,4- b]pyrazin-2-amine N-cyclopropyl-3-(4-((2,5-difluorophenyl)difluoromethyl)piperidin-1-yl)-5-methylpyrido[3,4- b]pyrazin-2-amine 2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)difluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile N-cyclopropyl-3-(4-((2,4-difluorophenyl)difluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine 2-(cyclopropylamino)-3-(4-((2,5-difluorophenyl)difluoromethyl)piperidin-1-yl)quinoxaline-6- carbonitrile (S)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4- b]pyrazine-7-carbonitrile (R)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4- b]pyrazine-7-carbonitrile (R)-3-(cyclopropylamino)-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4- b]pyrazine-7-carbonitrile (S)-3-(cyclopropylamino)-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4- b]pyrazine-7-carbonitrile N-cyclopropyl-3-(4-(pyridin-3-yloxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine N-cyclopropyl-3-(4-(4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine N-cyclopropyl-3-(4-(pyridin-2-yloxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine N-cyclopropyl-3-(4-(pyridin-4-yloxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2-methoxyphenyl)methanone, 2,2,2-trifluoroacetic acid salt 4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)benzonitrile (2-chlorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(3-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(phenyl)methanone (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,3-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt (3-chlorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone 3-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)benzonitrile (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(3-methoxyphenyl)methanone (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(o-tolyl)methanone, 2,2,2- trifluoroacetic acid salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,6-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt (2-chloro-5-fluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4- yl)methanone, 2,2,2-trifluoroacetic acid salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(3-fluorophenyl)methanone, 2,2,2- trifluoroacetic acid salt (6-chloro-2,3-difluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4- yl)methanone, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt (2-chloro-3-fluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4- yl)methanone, hydrogen chloride salt (2-chlorothiophen-3-yl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, hydrogen chloride salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(thiophen-2-yl)methanone, 2,2,2- trifluoroacetic acid salt 2-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)benzonitrile (2-chloro-6-fluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4- yl)methanone (S)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N,N- dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt (S)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N,N- dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt (R)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N,N- dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt (S)-(2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4- b]pyrazin-7-yl)(morpholino)methanone, 2,2,2-trifluoroacetic acid salt (R)-(2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4- b]pyrazin-7-yl)(morpholino)methanone, 2,2,2-trifluoroacetic acid salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2-(methylthio)phenyl)methanone, 2,2,2-trifluoroacetic acid salt 1-(4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)phenyl)ethanone, 2,2,2- trifluoroacetic acid salt 2,2,2-trifluoroacetic acid, 1-(4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4- yl)oxy)phenyl)ethanol salt (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(thiophen-3-yl)methanone, 2,2,2- trifluoroacetic acid salt (2-bromophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, 2,2,2- trifluoroacetic acid salt (2-bromopyridin-3-yl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, 2,2,2-trifluoroacetic acid salt 3-(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidine-4-carbonyl)-4-fluorobenzonitrile, 2,2,2-trifluoroacetic acid salt 4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)-N,N-dimethylbenzamide, 2,2,2-trifluoroacetic acid salt (R)-azetidin-1-yl(2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1- yl)pyrido[3,4-b]pyrazin-7-yl)methanone (R)-(2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4- b]pyrazin-7-yl)(3-fluoroazetidin-1-yl)methanone (S)-azetidin-1-yl(2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1- yl)pyrido[3,4-b]pyrazin-7-yl)methanone 7-chloro-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2-fluoro-5- (methylthio)phenyl)methanone, 2,2,2-trifluoroacetic acid salt (S)-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2- amine, 2,2,2-trifluoroacetic acid salt 4-chloro-3-(1-(7-chloro-2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidine-4- carbonyl)benzonitrile 3-(4-(5-cyano-2-(dimethylcarbamoyl)benzoyl)piperidin-1-yl)-2-(cyclopropylamino)-N,N- dimethylpyrido[3,4-b]pyrazine-7-carboxamide 2-(cyclopropylamino)-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-N,N-dimethylpyrido[3,4-b]pyrazine- 7-carboxamide N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt (R)-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2- amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(4-(methylthio)phenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(4-ethoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(1-(7-bromo-2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidine-4-carbonyl)-4- fluorobenzonitrile (2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-7- yl)(4-methylpiperazin-1-yl)methanone 2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-N,N-dimethylpyrido[3,4- b]pyrazine-5-carboxamide 2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazine-5- carbonitrile, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-5-morpholinopyrido[3,4-b]pyrazin- 2-amine, 2,2,2-trifluoroacetic acid salt N2-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-N5,N5-dimethylpyrido[3,4- b]pyrazine-2,5-diamine, 2,2,2-trifluoroacetic acid salt 3-(4-(2-chloro-5-fluorobenzoyl)piperazin-1-yl)-2-(cyclopropylamino)-N,N-dimethylpyrido[3,4- b]pyrazine-7-carboxamide N-cyclopropyl-2-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2- trifluoroacetic acid salt azetidin-1-yl(2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4- b]pyrazin-5-yl)methanone, 2,2,2-trifluoroacetic acid salt (2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-7- yl)(morpholino)methanone, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazine-5-carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxybenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazine-5- carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxybenzyl)piperazin-1-yl)-N,N-dimethylpyrido[3,4- b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt 4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)-3-fluorophenol, 2,2,2- trifluoroacetic acid salt 3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt N-cyclopropyl-3-(4-(2-fluoro-4-(methylthio)phenoxy)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2- amine, 2,2,2-trifluoroacetic acid salt N-cyclopropyl-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt N-ethyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2- trifluoroacetic acid salt 4-((1-(3-(cyclopropylamino)pyrazino[2,3-d]pyridazin-2-yl)piperidin-4-yl)oxy)-3-fluorophenol 3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt 4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)-3-fluorobenzonitrile, 22,2,2-trifluoroacetic acid salt 2-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-3-(isopropylamino)quinoxaline-6-carbonitrile, hydrogen chloride salt 2-(4-(2-chloro-5-(isopropylamino)benzoyl)piperidin-1-yl)-3-(isopropylamino)quinoxaline-6- carbonitrile 3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-2-(isopropylamino)pyrido[3,4-b]pyrazine-7- carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-2-(isopropylamino)-N,N-dimethylpyrido[3,4-b]pyrazine-7- carboxamide, 2,2,2-trifluoroacetic acid salt 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-2-(isopropylamino)-N,N-dimethylpyrido[3,4- b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-difluorobenzoyl)piperidin-1-yl)-2-(isopropylamino)pyrido[3,4-b]pyrazine-7-carbonitrile, 2,2,2-trifluoroacetic acid salt 3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-2-(isopropylamino)-N,N-dimethylpyrido[3,4-b]pyrazine-7- carboxamide, 2,2,2-trifluoroacetic acid salt 3-(4-(2,5-difluorobenzoyl)piperidin-1-yl)-2-(isopropylamino)-N,N-dimethylpyrido[3,4-b]pyrazine-7- carboxamide, 2,2,2-trifluoroacetic acid salt 3-(4-(2-fluoro-4-methoxybenzyl)piperidin-1-yl)-2-(isopropylamino)pyrido[3,4-b]pyrazine-7- carbonitrile, 2,2,2-trifluoroacetic acid salt (S)-N-(sec-butyl)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2- amine, 2,2,2-trifluoroacetic acid salt (R)-N-(sec-butyl)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2- amine, 2,2,2-trifluoroacetic acid salt 3-fluoro-4-((1-(3-(isopropylamino)pyrazino[2,3-d]pyridazin-2-yl)piperidin-4-yl)oxy)benzonitrile, 2,2,2-trifluoroacetic acid salt (R)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2- amine, 2,2,2-trifluoroacetic acid salt (2-fluoro-4-methoxyphenyl)(1-(3-(isopropylamino)pyrazino[2,3-d]pyridazin-2-yl)piperidin-4- yl)methanone, 2,2,2-trifluoroacetic acid salt 3-(4-(2-fluoro-4-methoxybenzyl)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2- trifluoroacetic acid salt 3-(4-((R)-(2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N-((1R,2R)-2- methylcyclopropyl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt 2-((2,2-difluoroethyl)amino)-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazine-7- carbonitrile, 2,2,2-trifluoroacetic acid salt 2-(tert-butylamino)-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile 3-fluoro-4-((1-(3-(isopropylamino)pyrazino[2,3-d]pyridazin-2-yl)piperidin-4-yl)oxy)phenol, 2,2,2- trifluoroacetic acid salt 2-((2,2-difluoroethyl)amino)-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-N,N-dimethylpyrido[3,4- b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine 2,2,2- trifluoroacetate N-isopropyl-3-(4-(3-methoxyphenoxy)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine 2,2,2- trifluoroacetate 3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-N-isopropyl-5,8-dimethylpyrazino[2,3-d]pyridazin-2- amine 2,2,2-trifluoroacetate 3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-N-isopropyl-8-methylpyrazino [2,3-d]pyridazin-2-amine N-cyclopropyl-3-(4-((4-fluorophenyl)sulfonyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine 2,2,2-trifluoroacetate 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-N-cyclopropylpyrazino[2,3-d]pyridazin-2-amine 2,2,2-trifluoroacetate 2-(4-(2,4-difluorophenoxy)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-3-amine N-cyclobutyl-2-(4-(2,4-difluorophenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-3-amine 3-(4-(2-fluoro-4-(fluoromethoxy)phenoxy)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2- amine

COMPOUND TABLE 2 MS(obs) (M⁺ + 1) 1. N-cyclopropyl-3-(3-(thiazol-5-ylmethyl)piperidin-1-yl)quinoxalin-2- amine,2,2,2-trifluoroacetic acid salt 2. N-cyclopropyl-3-(3-(4-fluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2- amine,2,2,2-trifluoroacetic acid salt 3. 2-(cyclopropylamino)-3-(1-(2,5-dichlorobenzyl)piperidin-4-yl)quinoxaline-6- 452.2 carbonitrile,2,2,2-trifluoroacetic acid salt 4. 2-(cyclopropylamino)-3-(1-(2,5-difluorobenzyl)piperidin-4-yl)quinoxaline-6- 420.3 carbonitrile,2,2,2-trifluoroacetic acid salt 5. 3-(1-(4-chlorobenzoyl)piperidin-4-yl)-2-(cyclopropylamino)quinoxaline-6- 432.25 carbonitrile,2,2,2-trifluoroacetic acid salt 6 N-cyclopropyl-3-(1-(2,4-difluorobenzyl)piperidin-4-yl)-7-methylpyrido[3,4- 410.3 b]pyrazin-2-amine,2,2,2-trifluoroacetic acid salt 7. N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)-2-methylpiperazin-1-yl)quinoxalin-2- 442.2 amine 8. (4-(3-(cyclopropylamino)quinoxalin-2-yl)-3-methylpiperazin-1-yl)(2,5- 456.2 dichlorophenyl)methanone,2,2,2-trifluoroacetic acid salt 9. N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)-3-isopropylpiperazin-1-yl)quinoxalin- 470.3 2-amine 10. N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)-3-methylpiperazin-1-yl)quinoxalin-2- 442.25. amine,2,2,2-trifluoroacetic acid salt

It is understood that R³, R⁴, R⁵, and R⁶ are substituents on carbon such that each of X¹-X⁴ that are carbon will have a substituent selected from R³, R⁴, R⁵, and R⁶ and that one or two of X¹-X⁴ are N, then one or two of R³, R⁴, R⁵, and R⁶ are absent.

EMBODIMENTS Embodiment (1)

A compound of Formula (I):

wherein:

R¹ is a heterocycloamino ring substituted with R^(a), R^(b), and R^(c) wherein:

-   -   R^(a) is —Z—Ar where Z is C₁₋₆ alkylene, C₁₋₆ haloalkylene, —O—,         —C(O)—, —NH—, or —S(O)n- wherein n is 0, 1, or 2; and Ar is         C₃₋₁₀ cycloalkyl, C₃₋₇ heterocycloalkyl, C₃₋₇         heterocycloalkenyl, C₆₋₁₀ aryl, or C₁₋₉ heteroaryl wherein C₃₋₁₀         cycloalkyl, C₃₋₇ heterocycloalkenyl, C₃₋₇ heterocycloalkyl,         C₆₋₁₀ aryl, and C₁₋₉ heteroaryl are optionally substituted with         1 to 3 substituents independently selected from C₁₋₆ alkyl,         halo, hydroxy, oxo, C₁₋₆ alkoxy, C₁₋₆ thioalkoxy, C₁₋₆         haloalkyl, C₁₋₆ hydroxyalkyl, C₁₋₆ haloalkoxy, C₁₋₆         alkylcarbonyl, C₁₋₆ alkylsulphonyl, cyano, C₂₋₁₂ alkoxyalkyloxy,         C₁₋₉ amide, or C₁₋₆ hydroxyalkyloxy; and     -   R^(b) and R^(c) are independently hydrogen, C₁₋₆ alkyl, hydroxy,         or halo;

R² is —OR^(e) or —NR^(d)R^(e) wherein R^(d) is hydrogen or C₁₋₆ alkyl and R^(e) is C₁₋₆ alkyl, C₁₋₆ haloalkyl, C₁₋₆ hydroxyalkyl, C₂₋₁₂ alkoxyalkyl, C₁₋₁₂ aminoalkyl, C₃₋₁₀ cycloalkyl, C₄₋₁₆ cycloalkylalkyl, C₆₋₁₀ aryl, C₁₋₉ heteroaryl, C₃₋₇ heterocyclyl, or C₃₋₇ heterocycloalkenyl wherein C₆₋₁₀ aryl, C₁₋₉ heteroaryl, C₃₋₇ heterocyclyl, and C₃₋₇ heterocycloalkenyl are optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, oxo, C₁₋₆ alkoxy, C₁₋₆ haloalkyl or C₁₋₆ haloalkoxy, or cyano;

all X¹-X⁴ are carbon or one or two of X¹-X⁴ are N and the rest of X¹-X⁴ are carbon;

R³, R⁴, R⁵, and R⁶ are independently absent, hydrogen, C₁₋₆ alkyl, halo, hydroxy, C₁₋₆ alkoxy, C₁₋₆ alkoxycarbonyl, C₁₋₆ haloalkyl, C₁₋₆ haloalkoxy, C₁₋₉ amide, C₃₋₇ heterocyclyl, C₁₋₈ alkylamino, or cyano;

or a pharmaceutically acceptable salt thereof

Embodiment 2

The compound or pharmaceutically acceptable salt of embodiment 1, wherein:

R¹ is a heterocycloamino ring of formula:

where X is carbon or nitrogen, and

R² is —OR^(e) or —NR^(d)R^(e) wherein R^(d) is hydrogen or C₁₋₆ alkyl; and R^(e) is C₁₋₆ alkyl, C₁₋₆ haloalkyl, C₁₋₆ hydroxyalkyl, C₂₋₁₂ alkoxyalkyl, C₁₋₁₂ aminoalkyl, C₃₋₁₀ cycloalkyl, C₃₋₁₀ oxocycloalkyl, phenyl, monocylic C₁₋₅ heteroaryl, or C₃₋₇ heterocyclylalkenyl wherein phenyl, C₁₋₉ heteroaryl, and C₃₋₇ heterocyclylalkenyl are optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, oxo, C₁₋₆ alkoxy, C₁₋₆ haloalkyl or C₁₋₆ haloalkoxy, or cyano.

Within the compounds in embodiment 2, in one group of compounds, R¹ is a heterocycloamino ring of formula

Embodiment 3

The compound or pharmaceutically acceptable salt of embodiment 1 or 2 or any groups contained therein, wherein R² is —NR^(d)R^(e). Within the compounds in embodiment 3, in one group of compounds, R^(d) is hydrogen.

Embodiment 4

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-3 and groups contained therein, wherein R¹ is a heterocycloamino ring of formula:

where X is carbon or nitrogen.

Within the compounds in embodiment 4, in one group of compounds, R¹ is a heterocycloamino ring of formula:

Embodiment 5

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-4 and groups contained therein, wherein all X¹-X⁴ are carbon.

Embodiment 6

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-5 and groups contained therein, wherein X¹-X⁴ are carbon and each of R³, R⁴, R⁵, and R⁶ are hydrogen.

Embodiment 7

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-4 and groups contained therein, wherein X¹, X³ and X⁴ are carbon and X² is CR³ or X¹, X² and X⁴ are carbon and X³ is CR³.

(a) Within the groups in embodiment 7, in one group of compounds each and R⁴, R⁵, and R⁶ are hydrogen and X² is CR³. Within groups of compounds in (a), in one group of compounds R³ is halo, C₁₋₆ alkyl, C₁₋₆ alkoxy or cyano. Within groups of compounds in (a), in one group of compounds R³ is cyano, methyl, methoxy, chloro or fluoro. Within groups of compounds in (a), in yet another group of compounds R³ is halo or cyano. Within groups of compounds in (a), in one group of compounds R³ is cyano or fluoro.

(b) Within the groups in embodiment 7, in another group of compounds each and R⁴, R⁵, and R⁶ are hydrogen and X³ is CR³. Within groups of compounds in (b), in one group of compounds R³ is halo, C₁₋₆ alkyl, C₁₋₆ alkoxy or cyano. Within groups of compounds in (b), in one group of compounds R³ is cyano, methyl, methoxy, chloro or fluoro. Within groups of compounds in (b), in one group of compounds R³ is cyano or fluoro.

Embodiment 8

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-4 and groups contained therein, wherein one or both of X² and X³ are nitrogen and the remaining X¹-X⁴ are carbon.

(a). Within groups in embodiment 8, in one group of compounds X² is N. Within groups of compounds in (a), in one group of compounds X² is N, X¹ is CR³ where R³ is hydrogen, halo, C₁₋₆ alkyl, C₁₋₆ alkoxy, cyano or hydroxy and R⁴ is absent, and each of R⁵ and R⁶ are hydrogen. Within groups of compounds in (a), in another group of compounds X² is N, X¹ is CR³ where R³ is fluoro, chloro, methyl, ethyl, cyano, or methoxy and R⁴ is absent, and each of R⁵ and R⁶ are hydrogen. Within groups of compounds in (a), in another group of compounds X² is N and R³ is absent, and each of R⁴, R⁵, and R⁶ are hydrogen.

(b). Within groups in embodiment 8, in another group of compounds X² is N, X³ is CR³ where R³ is hydrogen, C₁₋₆ alkyl, C₁₋₆ alkoxy, halo, or cyano and X¹ and X⁴ are carbon. Within groups of compounds in (b), in another group of compounds X² is N, X³ is CR³ where R³ is cyano, fluoro, chloro, methyl, ethyl, or methoxy and R⁴ is absent, and each of R⁵ and R⁶ are hydrogen. Within groups of compounds in (b), in another group of compounds X² is N, X³ is CR³ where R³ is cyano, fluoro, chloro, methyl, or methoxy and R⁴ is absent, and each of R⁵ and R⁶ are hydrogen.

(c). Within groups in embodiment 8, in another group of compounds X³ is N. Within groups of compounds in (c), in one group of compounds X³ is N, X² is CR³ where R³ is hydrogen, halo, C₁₋₆ alkyl, C₁₋₆ alkoxy, or cyano and R⁴ is absent, and each of R⁵ and R⁶ are hydrogen. Within groups of compounds in (c), in another group of compounds X³ is N, X² is CR³ where R³ is fluoro, chloro, methyl, ethyl, cyano, or methoxy and R⁴ is absent, and each of R⁵ and R⁶ are hydrogen. Within groups of compounds in (c), in another group of compounds X³ is N, X² is CR³ where R³ is fluoro, chloro, methyl, cyano, or methoxy and X¹ and X⁴ are CH. Within groups of compounds in (c), in another group of compounds X³ is N and each of R⁴, R⁵, and R⁶ are hydrogen.

(d). Within groups in embodiment 8, in yet another group of compounds X² and X³ are nitrogen. Within groups of compounds in (d), in one group of compounds and R⁴ each of R⁵ and R⁶ are hydrogen.

Embodiment 9

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-8 and groups contained therein, wherein R² is —NHR^(e).

Embodiment 10

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-8 and groups contained therein, wherein R² is —NHR^(e) wherein R^(e) is C₃₋₁₀ cycloalkyl. Within the groups in embodiment 10, in one group of compounds, R^(e) is cyclopropyl, cyclobutyl, cyclopentyl or cyclohexyl. Within the groups in embodiment 10, in another group of compounds, R^(e) is cyclopropyl.

Embodiment 11

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-8 and groups contained therein, wherein R² is —NHR^(e) wherein R^(e) is C₄₋₁₆ cycloalkylalkyl. Within the groups in embodiment 11, in one group of compounds, R^(e) is cyclopropylmethyl, cyclobutylmethyl, cyclopentylmethyl or cyclohexylmethyl. Within the groups in embodiment 10, in another group of compounds, R^(e) is cyclopropylmethyl.

Embodiment 12

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-8 and groups contained therein, wherein R² is —NHR^(e) wherein R^(e) is C₁₋₆ alkyl. Within the groups in embodiment 12, in one group of compounds, R^(e) is isobutyl, tert-butyl, n-propyl, isopropyl, 2-ethylbutyl, 4-methylpent-2-yl, 2,2-dimethylpropyl, 3,3-dimethylbutyl, 3-methylbutyl, but-2-yl. Within the groups in embodiment 12, in another group of compounds, R^(e) is isopropyl.

Embodiment 13

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-8 and groups contained therein, wherein R² is —NHR^(e) wherein R^(e) is hydroxyalkyl. Within the groups in embodiment 12, in one group of compounds, R^(e) is 2-hydroxyethyl, 3-hydroxypropyl, or (R)-3-hydroxyprop-2-yl.

Embodiment 14

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-8 and groups contained therein, wherein R² is —NHR^(e) wherein R^(e) is C₂₋₁₂ alkoxyalkyl. Within the groups in embodiment 12, in one group of compounds, R^(e) is 2-methoxyethyl, 3-methoxypropyl, 2-ethoxyethyl, 2-isopropoxyethyl, or 3-ethoxypropyl.

Embodiment 15

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-8 and groups contained therein, wherein R² is —NHR^(e) wherein R^(e) is C₁₋₁₂ aminoalkyl.

Embodiment 16

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-8 and groups contained therein, wherein R² is —NHR^(e) wherein R^(e) is C₁₋₆ haloalkyl. Within the groups in embodiment 12, in one group of compounds R^(e) is 2,2,2-trifluoroethyl, 2-fluoroethyl, 2,2-difluoroethyl, or 3,3,3-trifluoropropyl.

Embodiment 17

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-8 and groups contained therein, wherein R² is —NHR^(e) wherein R^(e) is C₃₋₇ heterocyclyl or C₃₋₇ heterocycloalkenyloptionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, C₁₋₆ alkoxy, C₁₋₆ haloalkyl or C₁₋₆ haloalkoxy, or cyano. Within the groups in embodiment 12, in one group of compounds, R^(e) is tetrahydropyran-4-yl, oxetan-3-yl, or of the formula:

Embodiment 18

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-8 and groups contained therein, wherein R² is —NHR^(e) wherein R^(e) is monocylic C₁₋₉ heteroaryl optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, C₁₋₆ alkoxy, haloalkyl or haloalkoxy, or cyano. Within the groups in embodiment 18, in one group of compounds, R^(e) is pyridin-3-yl, pyridin-2-yl, pyridin-4-yl, thia[1,3,4]diazol-2-yl, thiazol-2-yl, pyrimidin-2-yl, pyrimidin-5-yl, pyrazin-2-yl, pyrimidin-6-yl, pyridazin-3-yl, 1,2,4-triazin-3-yl, 5,6-dimethyl-1,2,4-triazin-3-yl, 3,4-dimethylisoxazol-5-yl, 2-hydroxypyridin-5-yl (tautomeric form pyridin-2(1H)-one), 2-methoxypyridin-5-yl, or isoxazol-3-yl.

Embodiment 19

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-8 and groups contained therein, wherein R² is —NHR^(e) wherein R^(e) is phenyl optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, C₁₋₆ alkoxy, haloalkyl or haloalkoxy, or cyano. Within the groups in embodiment 19, in one group of compounds, R^(e) is 2-bromophenyl, 3-bromophenyl, 4-bromophenyl, 4-fluorophenyl, phenyl, 4-trifluoromethoxyphenyl, 4-n-propylphenyl, 4-methylphenyl, 4-tert-butylphenyl, 2-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 4-isopropoxyphenyl, or 4-cyanophenyl.

Embodiment 20

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-19 and groups contained therein, wherein R¹ is a heterocycloamino ring of formula:

Within this group of compounds in another embodiment are compounds, wherein R¹ is a heterocycloamino ring of formula:

Embodiment 21

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-19 and groups contained therein, wherein R¹ is a heterocycloamino ring of formula:

Within this group of compounds in another embodiment are compounds, wherein R¹ is a heterocycloamino ring of formula:

Embodiment 22

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-21 wherein Z is C₁₋₆ alkyene. Within the groups in embodiment 22, in one group of compounds Z is —CH₂—, —CH(CH₃)—, or —(CH₂)₂, more preferably —CH₂—.

Embodiment 23

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-20 wherein Z is C₁₋₆ haloalkylene. Within the groups in embodiment 23, in one group of compounds Z is —*CHF—; —*CF(CH₃)—, or —CF₂— where the stereochemistry at *C is (RS), (R) or (S). Within the groups in embodiment 23, in one group of compounds Z is —*CHF— where the stereochemistry at *C is (RS), (R) or (S).

Embodiment 24

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-20 wherein Z is —O— provided Z is attached to a carbon atom in R¹.

Embodiment 25

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-21 wherein Z is —C(O)—.

Embodiment 26

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-21 wherein Z is SO₂.

Embodiment 27

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-20 wherein Z is —NH— provided Z is attached to a carbon atom in R¹.

Embodiment 28

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-27 wherein Ar is phenyl optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, C₁₋₆ alkoxy, C₁₋₆ haloalkyl, C₁₋₆ haloalkoxy, C₁₋₆ alkylsulphonyl, C₁₋₆ alkylcarbonyl, cyano, C₂₋₁₂ alkoxyalkyloxy, or C₁₋₆ hydroxyalkyloxy. Within the groups in embodiment 28, in one group of compounds in one group of compounds Ar is phenyl optionally substituted with 1 to 3 substituents independently selected from halo or cyano, preferably fluoro. Within the groups in embodiment 28, in another group of compounds Ar is phenyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 4-ethylphenyl, 3-isopropylphenyl, 4-ethoxyphenyl, 3-CF₃phenyl, 4-CF₃phenyl, 2-chlorophenyl, 3-chlorophenyl, 4-chlorophenyl, 4-chloromethylphenyl, 4-difluoromethylphenyl, 2-bromophenyl, 4-bromophenyl, 2-cyanophenyl, 3-cyanophenyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 4-isopropylphenyl, 3-bromophenyl, 4-methylsulfonylphenyl, 4-cyanophenyl, 4-tert-butylphenyl, 3-methoxyphenyl, 3-methoxyphenyl, 4-methoxyphenyl, 4-OCF₃phenyl, 2,3-dichlorophenyl, 3,4-dichlorophenyl, 3,5-dichlorophenyl, 2,4-dichlorophenyl, 2,5-dichlorophenyl, 2,6-dichlorophenyl, 2-chloro-4-methylsulfonylphenyl, 2,5-difluorophenyl, 2,6-difluorophenyl, 2,4-difluorophenyl, 3,4-difluorophenyl, 3,5-difluorophenyl, 3,4-dimethylphenyl, 4-fluoro-2-methylphenyl, 2-fluoro-5-methylphenyl, 5-fluoro-2-methylphenyl, 5-chloro-2-difluoromethoxyphenyl, 4-chloro-3-methylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2-bromo-5-chlorophenyl, 3-bromo-4-methylphenyl, 2-bromo-4-methylphenyl, 3-bromo-2-methylphenyl, 4-fluoro-3-methoxyphenyl, 2-bromo-5-methoxyphenyl, 3-bromo-4-methoxyphenyl, 4-bromo-2-chlorophenyl, 3-bromo-4-fluorophenyl, 4-bromo-2-fluorophenyl, 4-bromo-3-methylphenyl, 4-bromo-2-methylphenyl, 4-bromo-3-fluorophenyl, 4-chloro-2-methoxyphenyl, 5-bromo-2-fluorophenyl, 5-bromo-2-methylphenyl, 5-chloro-2-methylphenyl, 5-chloro-2-trifluoromethylphenyl, 4-chloro-2-methylphenyl, 4-chloro-3-methylphenyl, 2-chloro-5-methoxyphenyl, 3-chloro-4-methoxyphenyl, 2-chloro-4-fluorophenyl, 2-chloro-5-fluorophenyl, 3-chloro-4-fluorophenyl, 2-chloro-6-trifluoromethylphenyl, 2-chloro-5-iodophenyl, 4-chloro-2-hydroxyphenyl, 2-methoxy-4-methylphenyl, 2-methoxy-5-trifluoromethoxyphenyl, 2-methoxy-5-trifluoromethylphenyl, 2-chloro-6-difluoromethoxyphenyl, 5-chloro-2-propoxyphenyl, 2-methoxy-5-tert-butylphenyl, 4-chloro-2-fluorophenyl, 5-chloro-2-fluorophenyl, 4-cyano-2-fluorophenyl, 4-bromo-3-trifluoromethylphenyl, 2-fluoro-4-trifluoromethylphenyl, 3-cyano-4-isopropoxyphenyl, 2-fluoro-4-methylphenyl, 2-fluoro-4-methoxyphenyl, 4-fluoro-2-hydroxyphenyl, 4-chloro-2-trifluoromethylphenyl, 4-chloro-3-fluorophenyl, 2-chloro-5-trifluoromethylphenyl, 2,4-dimethoxyphenyl, 2,5-dimethoxyphenyl, 2-chloro-4-trifluoromethylphenyl, 3-cyano-4-fluorophenyl, 5-chloro-2-methoxyphenyl, 2-chloro-3,6-difluorophenyl, 2,3,5-trichlorophenyl, 2,6-difluoro-3-methylphenyl, 4-chloro-2,6-difluorophenyl, 2,4,6-trifluorophenyl, 2,4-difluoro-6-hydroxyphenyl, 2,4,5-trifluorophenyl, 2,4,6-trimethylphenyl, 2,3,4-trifluorophenyl, 4-chloro-2-5-dimethylphenyl, 3-chloro-5-fluoro-2-methylphenyl, 5-chloro-2,4-difluorophenyl, or 4-bromo-2,5-difluorophenyl. Within the groups in embodiment 28, in yet another group of compounds Ar is 5-chloro-2-fluorophenyl, 2,4-difluorophenyl, 2,5-difluorophenyl.

Embodiment 29

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-27 wherein Ar is C₁₋₉ heteroaryl optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, C₁₋₆ alkoxy, C₁₋₆ haloalkyl, C₁₋₆ haloalkoxy, C₁₋₆ alkylsulphonyl, C₁₋₆ alkylcarbonyl, cyano, C₂₋₁₂ alkoxyalkyloxy, or C₁₋₆ hydroxyalkyloxy. Within the groups in embodiment 29, in one group of compounds Ar is monocyclic C₁₋₉ heteroaryl optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, C₁₋₆ alkoxy, C₁₋₆ haloalkyl, C₁₋₆ haloalkoxy, C₁₋₆ alkylsulphonyl, C₁₋₆ alkylcarbonyl, cyano, C₂₋₁₂ alkoxyalkyloxy, or C₁₋₆ hydroxyalkyloxy. Within the groups in embodiment 29, in another group of compounds Ar is Ar is pyridine-2-yl, pyridine-3-yl, pyridine-4-yl, 2,5-dichlorothien-3-yl, benzofuran-3-yl, 2,5-difluoropyridin-3-yl, 2,5-dichloropyridin-4-yl, 5-chloro-2-fluoropyridin-2-yl, 3-fluoropyridin-2-yl, 3,6-dichloropyridin-2-yl, 5-methylisoxazol-3-yl, indol-5-yl, indol-6-yl, benzo[d][1,2,3]thiadiazol-5-yl, 3,5-dimethylisoxazol-4-yl, 5-chlorothien-2-yl, 5-bromothien-2-yl, 5-chloro-1,3-dimethylpyrazol-4-yl, 5-bromo-6-chloropyridin-3-yl, 3-methyl-[1,2,4]-oxadiazol-5-yl, thiazol-5-yl, 5-methyloxazol-2-yl, 3-fluoro-5-chloropyridin-2-yl, or 2-chloro-5-fluoropyridin-3-yl.

Embodiment 30

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-27 wherein Ar is Ar is C₃₋₇ heterocycloalkenyl optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, C₁₋₆ alkoxy, C₁₋₆ haloalkyl, C₁₋₆ haloalkoxy, C₁₋₆ alkylsulphonyl, C₁₋₆ alkylcarbonyl, cyano, C₂₋₁₂ alkoxyalkyloxy, or C₁₋₆ hydroxyalkyloxy. Within the groups in embodiment 29, in one group of compounds Ar is of the formula:

Embodiment 31

The compound or pharmaceutically acceptable salt of any of the previous embodiments 1-30 wherein R^(b) and R^(c) are hydrogen.

General Synthetic Scheme

Compounds of this invention can be made by the methods depicted in the reaction schemes shown below.

The starting materials and reagents used in preparing these compounds are either available from commercial suppliers such as Aldrich Chemical Co., (Milwaukee, Wis.), Bachem (Torrance, Calif.), or Sigma (St. Louis, Mo.) or are prepared by methods known to those skilled in the art following procedures set forth in references such as Fieser and Fieser's Reagents for Organic Synthesis, Volumes 1-17 (John Wiley and Sons, 1991); Rodd's Chemistry of Carbon Compounds, Volumes 1-5 and Supplementals (Elsevier Science Publishers, 1989); Organic Reactions, Volumes 1-40 (John Wiley and Sons, 1991), March's Advanced Organic Chemistry, (John Wiley and Sons, 4th Edition) and Larock's Comprehensive Organic Transformations (VCH Publishers Inc., 1989). These schemes are merely illustrative of some methods by which the compounds of this invention can be synthesized, and various modifications to these schemes can be made and will be suggested to one skilled in the art having referred to this disclosure. The starting materials and the intermediates, and the final products of the reaction may be isolated and purified if desired using conventional techniques, including but not limited to filtration, distillation, crystallization, chromatography and the like. Such materials may be characterized using conventional means, including physical constants and spectral data.

Unless specified to the contrary, the reactions described herein take place at atmospheric pressure over a temperature range from about −78° C. to about 150° C., more preferably from about 0° C. to about 125° C. and most preferably at about room (or ambient) temperature, e.g., about 20° C.

Compounds of Formula (I) where R¹ is heterocycloamino attached to the core ring via nitrogen atom, R² is NR^(d)R^(e), R^(b), R^(c), R³, R⁴, R⁵, R⁶, X¹, X², X³, X⁴, Ar, and Z are as defined in the Summary of the Invention can be prepared as illustrated and described in Scheme A below.

Treatment of a compound of formula 1 where R^(d) and R^(e) are defined in the Summary of the Invention with a compound of formula 2 where Hal is halo, R³, R⁴, R⁵, X¹, X², X³, and X⁴ are as defined in the Summary of the Invention, provides a compound of formula 3. Compounds of formula 1 are either commercially available or can be ready prepared by methods well known in the art. The reaction is carried out in a suitable organic solvent like dioxane, ethanol, tetrahydrofuran, dimethyl sulfoxide, N,N-dimethylformamide and the like (with or without a base such as sodium hydride, diisopropylethylamine or triethylamine) and takes upon heating at a suitable temperature between 20 to 150° C.

Compounds of formula 2 are either commercially available or can be readily prepared by methods well known in the art. For example, compounds of formula 2 where halo is chloro can be prepared by condensation of an aryl diamine with oxalic acid in a suitable aqueous acid, which upon treatment with a halogenating reagent such as thionyl chloride or phosphorous oxychloride and the like (with or without catalytic N,N-dimethylformamide) provides the compound of formula 2 were Hal is Cl. Compounds of formula 2 such as where X² or X³ is nitrogen, as well as where R³ or R⁴ or R⁵ is C₁₋₆ alkyl, cyano, and halo are commercially available.

Treatment of compound 3 with a heterocycloamino compound of formula 4 provides a compound of Formula (I). The reaction is carried out with or without base such as diisopropylethylamine and triethylamine, in a suitable organic solvent like dioxane, n-butanol, dimethyl sulfoxide and the like. Compounds of formula 4 are either commercially available or they can be readily prepared by methods well known in the art. For example, compounds of formula 4 where Z is oxygen can be prepared by Mitsunobu reaction between a piperidinol and an aryl alcohol. The reaction is usually carried out in the presence of a phosphine such as PPh₃, PMe₃, and the like and an activating reagent such as DEAD, DIAD and the like, in a suitable organic solvent such as tetrahydrofuran, toluene, dichloromethane, acetonitrile and the like. The reaction is usually carried out in the 0-80° C. temperature range.

Alternatively, a compound of formula 3 can be treated with piperazine which can be further modified by reductive amination, alkylation, arylation, amidation, sulfonylation and the like to provide a compound of Formula (I).

Compounds of Formula (I) can be converted to other compounds of Formula (I). For example, compounds of Formula (I) where Z is monosubstituted with fluorine can be prepared from the corresponding carbonyl by first reducing the carbonyl group to an alcohol group and then fluorination under conditions well known in the art. The reaction is typically carried out in the presence of a fluorinating agent such as DAST and the like, in a suitable solvent such as methanol and the like. The reaction is usually carried out in the −78 to 25° C. temperature range.

Alternatively, compounds of Formula (I) where Z is methylene can be prepared from the corresponding carbonyl compound by conditions well known in the art. The reaction is typically carried out in the presence of a reducing agent such as diisobutylaluminum hydride, borane-tetrahydrofuran, sodium borohydride and the like, in a suitable organic solvent such as dichloromethane, tetrahydrofuran, and the like.

Compounds of Formula (I) can also be prepared by reversing the order of addition of compounds of formula 1 and formula 4. Addition of compounds of formula 4 with compounds of formula 2 as defined in the Summary of the Invention, followed by addition of compounds of formula 1 as defined in the Summary of the Invention, provides a compound of Formula (I) with a different regiochemical outcome as that shown in Scheme A.

Detailed descriptions of some such transformations are provided in Working Examples below.

Alternatively, compounds of Formula (I) where R¹ is heterocycloamino attached to the core ring via carbon atom, R² is NR^(d)R^(e), R^(b), R^(c), R³, R⁴, R⁵, R⁶, X¹, X², X³, X⁴, Ar, and Z are as defined in the Summary of the Invention, can be prepared as illustrated and described in Scheme B below.

Compounds of formula 6 can be prepared by reaction of a compound of formula 3 with a heterocycloaminoalkenyl of formula 5 where PG is a nitrogen protecting group. The reaction is carried out in the presence of a common palladium catalyst such as Pd(PPh₃)₂Cl₂, Pd(PPh₃)₄, Pd₂dba₃ and the like and a base such as K₂C(O)₃ and the like in a suitable organic solvent such as acetonitrile, dioxane, N,N-dimethylformamide and the like. The reaction is usually heated up to 70-175° C. Compounds of formula 5 such as tetrahydropyridine are commercially available.

Compounds of formula 7 can be prepared by hydrogenation of a compound of formula 6. The reaction is usually carried out in the presence of a common palladium catalyst such as Pd on carbon and the like under a hydrogen atmosphere in a suitable organic solvent such as methanol, ethanol and the like. Acidic hydrolysis of the carbamate group provides the compound in formula 7.

Compounds of formula 7 can be converted to compounds of Formula (I). For example, compounds of formula 7 can be subjected to alkylation, arylation, sulfonylation, reductive amination and the like under conditions well known in the art.

Utility

The GPR6 receptor exhibits high expression in the central nervous system (CNS) with minimal expression in peripheral tissues. GPR6 is highly selectively enriched in D2 receptor expressing MSNs in the striatum. The striatum plays a central role in modulating important behaviors including movement, reward, and motivational processes. GPR6 is GPCR that exhibits receptor signaling via the Gs pathway. Thus, GPR6 agonist activity results in an increase in intracellular cAMP levels whereas antagonists or inverse agonists cause a decrease in cAMP levels. GPR6 activity is therefore functionally opposed to D2 receptor signaling which operates via the Gi pathway i.e., an agonist decreases the level of intracellular cAMP. As such, compounds that modulate the activity of GPR6 have utility in a variety of neurological and psychiatric disorders. For example, the pathological hallmark of Parkinson disease (PD) is neuronal cell loss within the substantia nigra. Degeneration of the nigrostriatal pathway causes reduction in the striatal concentration of dopamine which results in motor and nonmotor clinical manifestations. The major striatal targets of dopaminergic innervation reside in the medium spiny neurons (MSNs) of the striatopallidal (indirect) and striatonigral (direct) output pathways. The MSNs of the direct output pathway express D1 dopamine receptors whereas those in the indirect pathway express D2 receptors.

About 75% of Parkinson's disease patients are treated with levodopa, a prodrug for dopamine discovered over 50 years ago (Dopamine Replacement Therapy). Levodopa has common serious side effects including induced dyskinesia (LID), impulsive control disorders (ICD), psychotic symptoms and sleep disturbances. LID is progressive (90% of PD patients develop LID within 10 yrs). Irreversible adaptations occur in D1 receptor signaling in MSNs in rodent models of LID including reduced desensitization leading to hypersensitivity in the direct pathway. Genetic inactivation of D1 but not D2 receptors abolishes LID in mice. However blockade of D1 receptor signaling does not affect the antiparkinsonian efficacy of L-DOPA. cAMP pathways modulated by D1/D2 dopamine receptors in MSN have been implicated in LID in PD. Dopamine D2 receptors in MSN are Gi coupled, inhibiting cAMP generation. Antagonism or inverse agonism of Gs coupled GPR6 should decrease cAMP in MSNs—a functional alternative to dopamine mediated activation of D2 receptors. As such, compounds that modulate the activity of GPR6 have utility in a variety of neurological and psychiatric disorders. For example movement disorders including Parkinson's disease and Huntington's disease either alone or in combination with other agents are approved for the treatment of Parkinson's disease including L-DOPA, dopaminergic agonists, MAO B inhibitors, DOPA decarboxylase inhibitors and C(O)MT inhibitors. Other potential disease indications that could be treated by modulation of GPR6 include drug addiction and eating disorders, cognitive disorders, schizophrenia, bipolar disorders, and depression.

Testing

The GPR6 inhibitory activity of the compounds of the present invention can be tested using the in vitro assay and in vivo assay described in working Example I and II below.

Administration and Pharmaceutical Composition

In general, the compounds of this invention will be administered in a therapeutically effective amount by any of the accepted modes of administration for agents that serve similar utilities. Therapeutically effective amounts of compounds of Formula (I) may range from about 0.01 to about 100 mg per kg patient body weight per day, which can be administered in single or multiple doses. Preferably, the dosage level will be about 0.1 to about 50 mg/kg per day; more preferably about 0.5 to about 10 mg/kg per day. For oral administration, the compositions are preferably provided in the form of tablets containing about 1.0 to about 1000 milligrams of the active ingredient, particularly about 1.0, 5.0, 10, 15, 20, 25, 50, 75, 100, 150, 200, 250, 300, 400, 500, 600, 750, 800, 900, and 1000 milligrams of the active ingredient. The actual amount of the compound of this invention, i.e., the active ingredient, will depend upon numerous factors such as the severity of the disease to be treated, the age and relative health of the subject, the potency of the compound utilized, the route and form of administration, and other factors.

In general, compounds of this invention will be administered as pharmaceutical compositions by any one of the following routes: oral, systemic (e.g., transdermal, intranasal or by suppository), or parenteral (e.g., intramuscular, intravenous or subcutaneous) administration. The preferred manner of administration is oral using a convenient daily dosage regimen, which can be adjusted according to the degree of affliction. Compositions can take the form of tablets, pills, capsules, semisolids, powders, sustained release formulations, solutions, suspensions, elixirs, aerosols, or any other appropriate compositions.

The choice of formulation depends on various factors such as the mode of drug administration (e.g., for oral administration, formulations in the form of tablets, pills or capsules are preferred) and the bioavailability of the drug substance. Recently, pharmaceutical formulations have been developed especially for drugs that show poor bioavailability based upon the principle that bioavailability can be increased by increasing the surface area i.e., decreasing particle size. For example, U.S. Pat. No. 4,107,288 describes a pharmaceutical formulation having particles in the size range from 10 to 1,000 nm in which the active material is supported on a crosslinked matrix of macromolecules. U.S. Pat. No. 5,145,684 describes the production of a pharmaceutical formulation in which the drug substance is pulverized to nanoparticles (average particle size of 400 nm) in the presence of a surface modifier and then dispersed in a liquid medium to give a pharmaceutical formulation that exhibits remarkably high bioavailability.

The compositions are comprised of in general, a compound of formula (I) in combination with at least one pharmaceutically acceptable excipient. Acceptable excipients are non-toxic, aid administration, and do not adversely affect the therapeutic benefit of the compound of formula (I). Such excipient may be any solid, liquid, semi-solid or, in the case of an aerosol composition, gaseous excipient that is generally available to one of skill in the art.

Solid pharmaceutical excipients include starch, cellulose, talc, glucose, lactose, sucrose, gelatin, malt, rice, flour, chalk, silica gel, magnesium stearate, sodium stearate, glycerol monostearate, sodium chloride, dried skim milk and the like. Liquid and semisolid excipients may be selected from glycerol, propylene glycol, water, ethanol and various oils, including those of petroleum, animal, vegetable or synthetic origin, e.g., peanut oil, soybean oil, mineral oil, sesame oil, etc. Preferred liquid carriers, particularly for injectable solutions, include water, saline, aqueous dextrose, and glycols.

Compressed gases may be used to disperse a compound of this invention in aerosol form. Inert gases suitable for this purpose are nitrogen, carbon dioxide, etc.

Other suitable pharmaceutical excipients and their formulations are described in Remington's Pharmaceutical Sciences, edited by E. W. Martin (Mack Publishing Company, 18th ed., 1990).

The level of the compound in a formulation can vary within the full range employed by those skilled in the art. Typically, the formulation will contain, on a weight percent (wt %) basis, from about 0.01-99.99 wt % of a compound of formula (I) based on the total formulation, with the balance being one or more suitable pharmaceutical excipients. Preferably, the compound is present at a level of about 1-80 wt %.

The compounds of the present invention may be used in combination with one or more other drugs in the treatment of diseases or conditions for which compounds of the present invention or the other drugs may have utility, where the combination of the drugs together are safer or more effective than either drug alone. Such other drug(s) may be administered, by a route and in an amount commonly used therefore, contemporaneously or sequentially with a compound of the present invention. When a compound of the present invention is used contemporaneously with one or more other drugs, a pharmaceutical composition in unit dosage form containing such other drugs and the compound of the present invention can be used. However, the combination therapy may also include therapies in which the compound of the present invention and one or more other drugs are administered on different overlapping schedules. It is also contemplated that when used in combination with one or more other active ingredients, the compounds of the present invention and the other active ingredients may be used in lower doses than when each is used singly.

Accordingly, the pharmaceutical compositions of the present invention also include those that contain one or more other active ingredients, in addition to a compound of the present invention.

The above combinations include combinations of a compound of the present invention not only with one other active compound, but also with two or more other active compounds. Likewise, compounds of the present invention may be used in combination with other drugs that are used in the prevention, treatment, control, amelioration, or reduction of risk of the diseases or conditions for which compounds of the present invention are useful. Such other drugs may be administered, by a route and in an amount commonly used therefore, contemporaneously or sequentially with a compound of the present invention. When a compound of the present invention is used contemporaneously with one or more other drugs, a pharmaceutical composition containing such other drugs in addition to the compound of the present invention is preferred. Accordingly, the pharmaceutical compositions of the present invention also include those that also contain one or more other active ingredients, in addition to a compound of the present invention. The weight ratio of the compound of the present invention to the second active ingredient may be varied and will depend upon the effective dose of each ingredient. Generally, an effective dose of each will be used.

In one embodiment, the compound of the present invention may be administered in combination with anti-Alzheimer's agents, beta-secretase inhibitors, gamma-secretase inhibitors, HMG-CoA reductase inhibitors, NSAID's including ibuprofen, vitamin E, and anti-amyloid antibodies. In another embodiment, the compound of the present invention may be administered in combination with sedatives, hypnotics, anxiolytics, antipsychotics, antianxiety agents, cyclopyrrolones, imidazopyridines, pyrazolopyrimidines, minor tranquilizers, melatonin agonists and antagonists, melatonergic agents, benzodiazepines, barbiturates, 5HT-2 antagonists, PDE10 antagonists, and the like, such as: adinazolam, allobarbital, alonimid, alprazolam, amisulpride, amitriptyline, amobarbital, amoxapine, aripiprazole, bentazepam, benzoctamine, brotizolam, bupropion, busprione, butabarbital, butalbital, capuride, carbocloral, chloral betaine, chloral hydrate, clomipramine, clonazepam, cloperidone, clorazepate, chlordiazepoxide, clorethate, chlorpromazine, clozapine, cyprazepam, desipramine, dexclamol, diazepam, dichloralphenazone, divalproex, diphenhydramine, doxepin, estazolam, ethchlorvynol, etomidate, fenobam, flunitrazepam, flupentixol, fluphenazine, flurazepam, fluvoxamine, fluoxetine, fosazepam, glutethimide, halazepam, haloperidol, hydroxyzine, imipramine, lithium, lorazopam, lormetazepam, maprotiline, mecloqualone, melatonin, mephobarbital, meprobamate, methaqualone, midaflur, midazolam, nefazodone, nisobamate, nitrazopam, nortriptyline, olanzapine, oxazepam, paraldehyde, paroxetine, pentobarbital, perlapine, perphenazine, phenelzine, phenobarbital, prazepam, promethazine, propofol, protriptyline, quazepam, quetiapine, reclazepam, risperidone, roletamide, secobarbital, sertraline, suproclone, temazopam, thioridazine, thiothixene, tracazolate, kanylcypromaine, trazodone, triazolam, trepipam, tricetamide, triclofos, trifluoperazine, trimetozine, trimipramine, uldazepam, venlafaxine, zaleplon, ziprasidone, zolazepam, zolpidem, and salts thereof, and combinations thereof

In another embodiment, the compound of the present invention may be administered in combination with levodopa (with or without a selective extracerebral decarboxylase inhibitor such as carbidopa or benserazide), anticholinergics such as biperiden (optionally as its hydrochloride or lactate salt) and trihexyphenidyl(benzhexol)hydrochloride, C(O)MT inhibitors such as entacapone, MOA-B inhibitors, antioxidants, A2a adenosine receptor antagonists, cholinergic agonists, NMDA receptor antagonists, serotonin receptor antagonists and dopamine receptor agonists such as alentemol, bromocriptine, fenoldopam, lisuride, naxagolide, pergolide and prarnipexole. It will be appreciated that the dopamine agonist may be in the form of a pharmaceutically acceptable salt, for example, alentemol hydrobromide, bromocriptine mesylate, fenoldopam mesylate, naxagolide hydrochloride and pergolide mesylate. Lisuride and pramipexol are commonly used in a non-salt form.

In another embodiment, the compound of the present invention may be administered in combination with a compound from the phenothiazine, thioxanthene, heterocyclic dibenzazepine, butyrophenone, diphenylbutylpiperidine and indolone classes of neuroleptic agent. Suitable examples of phenothiazines include chlorpromazine, mesoridazine, thioridazine, acetophenazine, fluphenazine, perphenazine and trifluoperazine. Suitable examples of thioxanthenes include chlorprothixene and thiothixene. An example of a dibenzazepine is clozapine. An example of a butyrophenone is haloperidol. An example of a diphenylbutylpiperidine is pimozide. An example of an indolone is molindolone. Other neuroleptic agents include loxapine, sulpiride and risperidone. It will be appreciated that the neuroleptic agents when used in combination with the subject compound may be in the form of a pharmaceutically acceptable salt, for example, chlorpromazine hydrochloride, mesoridazine besylate, thioridazine hydrochloride, acetophenazine maleate, fluphenazine hydrochloride, flurphenazine enathate, fluphenazine decanoate, trifluoperazine hydrochloride, thiothixene hydrochloride, haloperidol decanoate, loxapine succinate and molindone hydrochloride. Perphenazine, chlorprothixene, clozapine, haloperidol, pimozide and risperidone are commonly used in a non-salt form. Thus, the compound of the present invention may be administered in combination with acetophenazine, alentemol, aripiprazole, amisulpride, benzhexol, bromocriptine, biperiden, chlorpromazine, chlorprothixene, clozapine, diazepam, fenoldopam, fluphenazine, haloperidol, levodopa, levodopa with benserazide, levodopa with carbidopa, lisuride, loxapine, mesoridazine, molindolone, naxagolide, olanzapine, pergolide, perphenazine, pimozide, pramipexole, quetiapine, risperidone, sulpiride, tetrabenazine, trihexyphenidyl, thioridazine, thiothixene, trifluoperazine or ziprasidone.

In another embodiment, the compound of the present invention may be administered in combination with an anti-depressant or anti-anxiety agent, including norepinephrine reuptake inhibitors (including tertiary amine tricyclics and secondary amine tricyclics), selective serotonin reuptake inhibitors (SSRIs), monoamine oxidase inhibitors (MAOIs), reversible inhibitors of monoamine oxidase (RIMAs), serotonin and noradrenaline reuptake inhibitors (SNR1s), corticotropin releasing factor (CRF) antagonists, adrenoreceptor antagonists, neurokinin-1 receptor antagonists, atypical anti-depressants, benzodiazopines, 5-HTA agonists or antagonists, especially 5-HTA partial agonists, and corticotropin releasing factor (CRF) antagonists. Specific agents include: amitriptyline, clomipramine, doxepin, imipramine and trimipramine; amoxapine, desipramine, maprotiline, nortriptyline and protriptyline; fluoxetine, fluvoxamine, paroxetine and sertraline; isocarboxazid, phenelzine, tranylcypromine and selegiline; moclobemide, venlafaxine; duloxetine; aprepitant; bupropion, lithium, nefazodone, trazodone and viloxazine; alprazolam, chlordiazepoxide, clonazopam, chlorazepate, diazopam, halazepam, lorazepam, oxazopam and prazepam; buspirone, flesinoxan, gepirone and ipsapirone, and pharmaceutically acceptable salts thereof.

EXAMPLES

The following preparations of the intermediate (References) and compounds of Formula (I) (Examples) are given to enable those skilled in the art to more clearly understand and to practice the present invention. They should not be considered as limiting the scope of the invention, but merely as being illustrative and representative thereof

SYNTHETIC EXAMPLES Reference A Synthesis of 3-chloro-N-cyclopropylquinoxalin-2-amine

A solution of 2,3-dichloroquinoxaline (400 mg, 2.010 mmol), cyclopropanamine (149 mg, 2.61 mmol) and N-ethyl-N-isopropylpropan-2-amine (526 μl, 3.01 mmol) in dioxane (2871 μl) was heated at 80° C. for 2 days. ISCO purification (10-40% EtOAc/hexanes) afforded the title compound as a light yellow solid.

Utilizing similar reaction conditions described above, following compounds were synthesized using commercially available amines and quinoxalines:

3-chloro-2-(cyclopropylamino)quinoxaline-6-carbonitrile; 3-chloro-N-cyclopropyl-6-fluoroquinoxalin-2-amine; 3-chloro-N-cyclopropyl-6,7-difluoroquinoxalin-2-amine; 3-chloro-2-(isopropylamino)quinoxaline-6-carbonitrile; 3-chloro-N-(2,2-difluoroethyl)pyrido-[3,4-b]pyrazin-2-amine; 3-chloro-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine; 3,8-dichloro-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine; 3-chloro-N-cyclopropyl-7-methylpyrido[3,4-b]pyrazin-2-amine; 3-chloro-N-cyclopropyl-5-methylpyrido[3,4-b]pyrazin-2-amine; 3-chloro-2-(cyclobutylamino)quinoxaline-6-carbonitrile; 3-chloro-2-((2-fluoroethyl)amino)-quinoxaline-6-carbonitrile; 3-chloro-N-(3-methoxypropyl)quinoxalin-2-amine; 3-chloro-2-((3,3,3-trifluoropropyl)amino)quinoxaline-6-carbonitrile; 6-bromo-3-chloro-N-cyclopropylquinoxalin-2-amine; 7-bromo-3-chloro-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, and 3,7-dichloro-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine.

Reference B Synthesis of 5-bromo-3-chloro-N-cyclopropylquinoxalin-2-amine and 8-bromo-3-chloro-N-cyclopropylquinoxalin-2-amine

A solution of 5-bromo-2,3-dichloroquinoxaline (250 mg, 0.899 mmol), cyclopropanamine (71.7 μl, 1.034 mmol) and N-ethyl-N-isopropylpropan-2-amine (157 μl, 0.899 mmol) in dioxane (1285 μl) was heated at 80° C. overnight. ISCO purification (20-80% EtOAc/Hexanes) yielded both pure title compounds as yellow solids.

Reference C Synthesis of N-cyclopropyl-3-(piperazin-1-yl)quinoxalin-2-amine dihydrochloride

Step 1: tert-butyl 4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazine-1-carboxylate

A solution of 3-chloro-N-cyclopropylquinoxalin-2-amine (503 mg, 2.290 mmol), tert-butyl piperazine-1-carboxylate (640 mg, 3.43 mmol) and DIPEA (1200 μl, 6.87 mmol) in dioxane (4580 μl) was stirred at 140° C. overnight. ISCO purification (10-70% EtOAc/hexanes) afforded the title compound as an ivory solid.

Step 2: N-cyclopropyl-3-(piperazin-1-yl)quinoxalin-2-amine dihydrochloride

A solution of tert-butyl 4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazine-1-carboxylate (127 mg, 0.344 mmol) in dioxane (859 μl) was treated with HCl (859 μl, 3.44 mmol, 4 M in dioxane) at RT and the reaction stirred for 4 h. The solvent was removed under reduced pressure to afford the title compound as a tan solid.

Following the procedure described above, following compounds were synthesized using commercially available starting materials.

2-(cyclopropylamino)-3-(piperazin-1-yl)quinoxaline-6-carbonitrile; N-cyclopropyl-6-fluoro-3-(piperazin-1-yl)quinoxalin-2-amine; 3-(piperazin-1-yl)-N-(pyridin-3-yl)quinoxalin-2-amine; 2-(isopropylamino)-3-(piperazin-1-yl)quinoxaline-6-carbonitrile; 2-(cyclobutylamino)-3-(piperazin-1-yl)quinoxaline-6-carbonitrile; and N-cyclopropyl-6,7-difluoro-3-(piperazin-1-yl)quinoxalin-2-amine

Reference D Synthesis of 2-chloro-3-(piperazin-1-yl)quinoxaline, hydrogen chloride salt

Step 1: tert-butyl 4-(3-chloroquinoxalin-2-yl)piperazine-1-carboxylate

A solution of 2,3-dichloroquinoxaline (2 g, 10.05 mmol), tert-butyl piperazine-1-carboxylate (2.059 g, 11.05 mmol) and N-ethyl-N-isopropylpropan-2-amine (2.63 ml, 15.07 mmol) in dioxane (10.05 ml) was heated at 80° C. for 18 h. ISCO purification (5-10% EtOAc in hexanes) afforded the title compound as a yellow oil.

Step 2: 2-chloro-3-(piperazin-1-yl)quinoxaline, hydrogen chloride salt

A solution of tert-butyl 4-(3-chloroquinoxalin-2-yl)piperazine-1-carboxylate (243 mg, 0.697 mmol) in dioxane (1742 μl) was treated with HCl (1393 μl, 5.57 mmol, 4 M in dioxane) dropwise at RT and the resulting reaction mixture was stirred overnight. The solvent was removed under reduced pressure and the title compound was obtained as a yellow solid.

Reference E Synthesis of 3-chloro-N-(pyridin-3-yl)quinoxalin-2-amine

To a solution of 2,3-dichloroquinoxaline (10 g, 50.2 mmol) in ethanol (50 mL) was added pyridin-3-amine (4.73 g, 50.2 mmol). The reaction mixture was stirred at 20° C. for 2 h. The reaction mixture was poured into water and extracted with EtOAc. The organic layer was dried and concentrated under reduced pressure to yield the title compound as an orange-brown solid.

Reference F Synthesis of 3-chloro-2-((6-methoxypyridin-3-yl)amino)quinoxaline-6-carbonitrile

To a suspension of NaH (10.71 mg, 0.268 mmol, 60% in mineral oil) in THF (1116 μl) was added 6-methoxypyridin-3-amine (26.8 μl, 0.245 mmol). The mixture was stirred at RT for 30 min before 2,3-dichloroquinoxaline-6-carbonitrile (50 mg, 0.223 mmol) was added. The reaction mixture was stirred for 12 h at 70° C., then for 48 h at RT. ISCO purification (0-60% EtOAc/hexanes) afforded the title compound as a yellow solid.

Following the procedure described above, 3-chloro-2-(pyridin-3-ylamino)-quinoxaline-6-carbonitrile was synthesized.

Reference G Synthesis of 3-chloro-N-(pyrazin-2-yl)quinoxalin-2-amine

A suspension of 2,3-dichloroquinoxaline (200 mg, 1.005 mmol) and pyrazin-2-amine (191 mg, 2.010 mmol) in DMF (3 ml) was treated with NaH (80 mg, 2.010 mmol, 60% in mineral oil). Stirring was continued for 2 h at 15° C., then the reaction mixture was poured into water, extracted with EtOAc, dried over anhydrous sodium sulfate, filtered and concentrated to give the title compound. The crude material was used without further purification.

Following the procedure described above, following compounds were synthesized using commercially available starting materials.

3-chloro-N-(pyrimidin-4-yl)quinoxalin-2-amine; 3-chloro-N-(pyridazin-3-yl)quinoxalin-2-amine; 3-chloro-N-(1,2,4-triazin-3-yl)quinoxalin-2-amine; 3-chloro-N-(5,6-dimethyl-1,2,4-triazin-3-yl)quinoxalin-2-amine; 3-chloro-N-(pyridin-4-yl)quinoxalin-2-amine; 3-chloro-N-(pyridin-2-yl)quinoxalin-2-amine; N-(3-chloroquinoxalin-2-yl)-3,4-dimethylisoxazol-5-amine; and N-(3-chloroquinoxalin-2-yl)isoxazol-3-amine.

Reference H Synthesis of 3-chloro-N-(2,2,2-trifluoroethyl)quinoxalin-2-amine

A suspension of Et₃N (0.420 ml, 3.01 mmol), 2,3-dichloroquinoxaline (200 mg, 1.005 mmol), and 2,2,2-trifluoroethanamine (199 mg, 2.010 mmol) in DMSO (5 ml) was heated at 120° C. under microwave irradiation for 1 h. The reaction mixture was concentrated under reduced pressure to give the title compound, which was used without further purification.

Following the procedure described above, 3-chloro-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile was synthesized.

Reference I Synthesis of 8-chloro-N-cyclopropyl-3-(piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine

A mixture of 3,8-dichloro-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine (100 mg, 0.392 mmol) and piperazine (338 mg, 3.92 mmol) in EtOH (10 ml) was heated at 40° C. for 3 h. The reaction was concentrated to dryness and partitioned between EtOAc and water. The insoluble material was collected by filtration then dried under vacuum to give the title compound as a tan solid.

Reference J Synthesis of piperazin-1-yl(3-(trifluoromethyl)phenyl)methanone, hydrogen chloride salt

Step 1: tert-butyl 4-(3-(trifluoromethyl)benzoyl)piperazine-1-carboxylate

A solution of 3-(trifluoromethyl)benzoic acid (1.22 g, 6.44 mmol) and HATU (2.45 g, 6.44 mmol) in DMF (16.1 mL) and iPr₂NEt (16.1 mmol, 2.81 mL) was stirred at RT for 30 min, followed by the addition of tert-butyl piperazine-1-carboxylate (1.2 g, 6.44 mmol). The resulting reaction mixture was stirred at RT overnight. Purification by column chromatography (25% EtOAc/hexanes) afforded the title compound as a yellow solid.

Step 2: piperazin-1-yl(3-(trifluoromethyl)phenyl)methanone, hydrogen chloride salt

A solution of tert-butyl 4-(3-(trifluoromethyl)benzoyl)piperazine-1-carboxylate (600 mg, 1.674 mmol) in dioxane (5.58 mL) was treated with HCl (3.35 mL, 13.39 mmol, 4 M in dioxane) at RT. After stirring for 12 h, the reaction mixture was diluted with hexanes and filtered. The solid was dissolved in MeOH and the solvent was removed under reduced pressure to afford the title compound as a white solid.

Following the procedure described above, following compounds were synthesized using commercially available carboxylic acids.

(4-(methylsulfonyl)phenyl)(piperazin-1-yl)methanone, hydrogen chloride salt; (2,5-dichlorophenyl)(piperazin-1-yl)methanone, hydrogen chloride salt; (2,5-dichlorophenyl)-(piperazin-1-yl)methanone, hydrogen chloride salt; (3-chloro-4-methoxyphenyl)(piperazin-1-yl)methanone, hydrogen chloride salt; (3,5-dichlorophenyl)(piperazin-1-yl)methanone, hydrogen chloride salt; (3-chlorophenyl)(piperazin-1-yl)methanone, hydrogen chloride salt; (2,3-dichlorophenyl)(piperazin-1-yl)methanone, hydrogen chloride salt; (5-methylisoxazol-3-yl)(piperazin-1-yl)methanone, hydrogen chloride salt; (4-chlorophenyl)(piperazin-1-yl)methanone, hydrogen chloride salt; and (4-chloro-2-fluorophenyl)(piperazin-1-yl)methanone hydrogen chloride salt.

Reference K Synthesis of piperazin-1-yl(4-(trifluoromethyl)phenyl)methanone 2,2,2-trifluoroacetate

Step 1: tert-butyl 4-(4-(trifluoromethyl)benzoyl)piperazine-1-carboxylate

4-(Trifluoromethyl)benzoic acid (1.531 g, 8.05 mmol) and HATU (3.06 g, 8.05 mmol) were dissolved in DMF (20.1 mL) at RT, then iPr₂NEt (3.33 mL, 20.13 mmol) was added and the solution stirred for 30 min. tert-Butyl piperazine-1-carboxylate (1.5 g, 8.05 mmol) was then added and stirring continued for 16 h.

ISCO purification yielded the title compound as a yellow oil.

Step 2: piperazin-1-yl(4-(trifluoromethyl)phenyl)methanone 2,2,2-trifluoroacetate

A solution of tert-butyl 4-(4-(trifluoromethyl)benzoyl)piperazine-1-carboxylate (1.78 g, 4.97 mmol) in DCM (9.9 mL) was treated with TFA (64.6 mmol, 5 mL) dropwise via syringe at RT. The resulting reaction mixture was stirred until complete by LCMS, then quenched with sat. NaHCO₃ and extracted with DCM. The organic layers were combined and dried over MgSO₄. Purification by column chromatography (15% MeOH/DCM) afforded the title compound as a yellow solid.

Reference L Synthesis of 1-(pyridin-3-ylmethyl)piperazine dihydrochloride salt

Step 1: tert-butyl 4-(pyridin-3-ylmethyl)piperazine-1-carboxylate

A solution of tert-butyl piperazine-1-carboxylate (306 mg, 1.643 mmol) and nicotinaldehyde (157 μl, 1.643 mmol) in DCE (5476 μl) was treated with sodium triacetoxyborohydride (487 mg, 2.300 mmol) at RT. The resulting reaction mixture was stirred at RT for 2 h. Purification by column chromatography (50% EtOAc/hexanes, then 10% MeOH/DCM) gave the title compound as a clear oil.

Step 2: 1-(pyridin-3-ylmethyl)piperazine dihydrochloride salt

A solution of tert-butyl 4-(pyridin-3-ylmethyl)piperazine-1-carboxylate (359 mg, 1.29 mmol) in dioxane (4.31 mL) was treated with HCl (2.58 mL, 10.35 mmol, 4 M in dioxane) dropwise at RT and the resulting reaction mixture was stirred for 18 h. After dilution with hexanes, the reaction mixture was filtered and the solid obtained was dissolved in MeOH. The solvent was removed under reduced pressure to afford the title compound as an ivory solid.

Following the procedure described above, following compounds were synthesized using commercially available aldehydes:

1-(pyridin-4-ylmethyl)piperazine, dihydrogen chloride salt; 1-(pyridin-2-ylmethyl)piperazine, dihydrogen chloride salt; 1-(3-bromobenzyl)piperazine, hydrogen chloride salt; 1-(5-chloro-2-(difluoromethoxy)benzyl)piperazine, hydrogen chloride salt; 1-(4-fluorobenzyl)piperazine, hydrogen chloride salt; 1-(2,5-dimethylbenzyl)piperazine, hydrogen chloride salt; 1-(2,4-difluorobenzyl)piperazine, hydrogen chloride salt; 1-(2,4,5-trifluorobenzyl)piperazine, hydrogen chloride salt; 1-(2,5-difluorobenzyl)piperazine, hydrogen chloride salt; 1-(5-chloro-2-fluorobenzyl)piperazine, hydrogen chloride salt; 1-(2,5-dichlorobenzyl)piperazine, hydrogen chloride salt; and 1-(2,6-dichlorobenzyl)piperazine, hydrogen chloride salt.

Reference M Synthesis of (2-chloro-4-(methylsulfonyl)phenyl)(piperazin-1-yl)methanone, hydrogen chloride salt

Step 1: tert-butyl 4-(2-chloro-4-(methylsulfonyl)benzoyl)piperazine-1-carboxylate

A solution of 2-chloro-4-(methylsulfonyl)benzoic acid (550 mg, 2.344 mmol) in DCM (7813 μl) and DMF (2 drops) was treated with oxalyl chloride (411 μl, 4.69 mmol) at RT and the reaction mixture was stirred for 2 h. A solution of tert-butyl piperazine-1-carboxylate (960 mg, 5.16 mmol) and Et₃N (719 μl, 5.16 mmol) in DCM (4.6 mL) was cooled to 0° C. and the crude acid chloride solution was added dropwise. The reaction mixture was allowed to warm up to RT and stirred for 3 h. ISCO purification (75% EtOAc/hexanes) afforded the title compound as a white solid.

Step 2: (2-chloro-4-(methylsulfonyl)phenyl)(piperazin-1-yl)methanone, hydrogen chloride salt

A solution of tert-butyl 4-(2-chloro-4-(methylsulfonyl)benzoyl)piperazine-1-carboxylate (581 mg, 1.442 mmol) in dioxane (4.81 mL) was treated with HCl (3605 μl, 14.42 mmol, 4 M in dioxane) and the resulting reaction mixture stirred at RT overnight. The solvent was removed to afford the title compound as a white solid.

Following the procedure described above, (3,6-dichloropyridin-2-yl)(piperazin-1-yl)methanone, dihydrogen chloride salt was synthesized using commercially available carboxylic acid.

Reference N Synthesis of 4-(2,5-difluorophenoxyl)piperidine hydrochloride

Step 1: tert-butyl 4-(2,5-difluorophenoxyl)piperidine-1-carboxylate

To a solution of tert-butyl 4-hydroxypiperidine-1-carboxylate (150 mg, 0.745 mmol) in THF (2484 μl) was added 2,5-difluorophenol (107 mg, 0.820 mmol) and triphenylphosphine (235 mg, 0.894 mmol). The mixture was cooled to 0° C. and DEAD (487 μl, 1.230 mmol, 40% wt in PhMe) was added dropwise. The mixture was then heated at 65° C. for 7 h then at RT for 18 h. ISCO purification (0-100% EtOAc/hexanes) yielded the title compound as a colorless oil.

Step 2: 4-(2,5-difluorophenoxyl)piperidine hydrochloride

To a solution of tert-butyl 4-(2,5-difluorophenoxyl)piperidine-1-carboxylate (71 mg, 0.227 mmol) in dioxane (755 μl) was added HCl (283 μl, 1.133 mmol, 4 M in dioxane). The mixture was stirred at RT for 16 h then concentrated under reduced pressure to afford the title compound as a white solid.

Following the procedure described above, following compounds were synthesized using commercially available aryl alcohols:

4-(2,4,6-trifluorophenoxyl)piperidine hydrochloride; 4-(5-chloro-2-fluorophenoxy)-piperidine hydrochloride; and 4-(4-chloro-2-fluorophenoxy)piperidine hydrochloride.

Reference O Synthesis of (2-fluorophenyl)(piperidin-4-yl)methanone hydrochloride

Step 1: tert-butyl 4-(2-fluorobenzoyl)piperidine-1-carboxylate

To a −78° C. solution of 1-bromo-2-fluorobenzene (88 μl, 0.808 mmol) in THF (4080 μl) was added n-BuLi (1154 μl, 1.616 mmol, 1.4 M in PhMe) dropwise. After stirring at −78° C. for 15 min, a solution of tert-butyl 4-(methoxy(methyl)carbamoyl)piperidine-1-carboxylate (200 mg, 0.734 mmol) in THF (1 mL) was added dropwise. The ice bath was removed and the reaction mixture was warmed to RT then stirred for 2 h. The solution was cooled to −30° C. and sat. aq. NH₄Cl (10 mL) was added. Upon reaching RT, the solution was diluted with EtOAc and the organic layer was washed with H₂O. The solvents were removed under reduced pressure and then ISCO purification (0-100% EtOAc/hexanes) yielded the title compound as a yellow oil.

Step 2: (2-fluorophenyl)(piperidin-4-yl)methanone hydrochloride

To a solution of tert-butyl 4-(2-fluorobenzoyl)piperidine-1-carboxylate (125 mg, 0.407 mmol) in dioxane (1356 μl) was added HCl (508 μl, 2.033 mmol, 4 M in dioxane). The mixture was stirred at 45° C. for 2 h then the solvents were removed under reduced pressure to afford the title compound as a light yellow solid.

Following the procedure described above, following compounds were synthesized using commercially available aryl bromides:

(2-fluorophenyl)(piperidin-4-yl)methanone hydrochloride; (2,5-difluorophenyl)-(piperidin-4-yl)methanone hydrochloride; piperidin-4-yl(2,4,6-trifluorophenyl)methanone hydrochloride; (4-chloro-2,6-difluorophenyl)(piperidin-4-yl)methanone hydrochloride; (4-chloro-2-fluorophenyl)(piperidin-4-yl)methanone hydrochloride; (5-chloro-2-fluorophenyl)(piperidin-4-yl)methanone hydrochloride; and (2,4-difluorophenyl)(piperidin-4-yl)methanone hydrochloride; (2-methoxyphenyl)(piperidin-4-yl)methanone hydrochloride; (2-chlorophenyl)(piperidin-4-yl)methanone hydrochloride; phenyl(piperidin-4-yl)methanone hydrochloride; (2,3-difluorophenyl)(piperidin-4-yl)methanone hydrochloride; (3-chlorophenyl)(piperidin-4-yl)methanone hydrochloride; piperidin-4-yl(o-tolyl)methanone hydrochloride; (2,6-difluorophenyl)(piperidin-4-yl)methanone hydrochloride; (2-chloro-5-fluorophenyl)(piperidin-4-yl)methanone hydrochloride; (3-fluorophenyl)(piperidin-4-yl)methanone hydrochloride; piperidin-4-yl(thiophen-2-yl)methanone, hydrogen chloride salt; (2-chlorothiophen-3-yl)(piperidin-4-yl)methanone hydrochloride; piperidin-4-yl(thiophen-3-yl)methanone hydrochloride; 3-(piperidine-4-carbonyl)benzonitrile hydrochloride; (2-(methylthio)phenyl)(piperidin-4-yl)methanone hydrochloride; 4-fluoro-3-(piperidine-4-carbonyl)benzonitrile hydrochloride; (6-chloro-2,3-difluorophenyl)(piperidin-4-yl)methanone hydrochloride; (2-chloro-3-fluorophenyl)(piperidin-4-yl)methanone hydrochloride.

Reference P Synthesis of (R/S)-4-((2,4-difluorophenyl)fluoromethyl)piperidine hydrochloride

Step 1: tert-butyl 4-((2,4-difluorophenyl)(hydroxy)methyl)piperidine-1-carboxylate

To a 0° C. solution of tert-butyl 4-(2,4-difluorobenzoyl)piperidine-1-carboxylate (1.28 g, 3.93 mmol) in MeOH (15.74 ml) was added NaBH₄ (0.372 g, 9.84 mmol). The ice bath was removed and the reaction mixture stirred for 2 h at RT then was quenched with sat. aq. NH₄Cl. The organic layer was extracted with EtOAc, washed with H₂O and dried over MgSO₄. The solvent was removed under reduced pressure to yield the title compound as a white hygroscopic solid.

Step 2: tert-butyl 4-((2,4-difluorophenyl)fluoromethyl)piperidine-1-carboxylate

To a −78° C. solution of tert-butyl 4-((2,4-difluorophenyl)(hydroxy)methyl)piperidine-1-carboxylate (200 mg, 0.611 mmol) in CH₂Cl₂ (3055 μl) was added DAST (242 μl, 1.833 mmol). The mixture was stirred at −78° C. for 30 min., then quenched with MeOH. ISCO purification (0-100% EtOAc/hexanes) afforded the title compound as a colorless oil.

Step 3: (R/S)-4-((2,4-difluorophenyl)fluoromethyl)piperidine hydrochloride

To a solution of tert-butyl 4-((2,4-difluorophenyl)fluoromethyl)piperidine-1-carboxylate (148 mg, 0.449 mmol) in dioxane (1498 μl) was added HCl (337 μl, 1.348 mmol, 4 M in dioxane). The mixture was heated at 45° C. for 16 h then concentrated under reduced pressure to yield the title compound as a white solid.

Note: Optically pure compounds were obtained by chiral SFC separation of racemic compound.

Following the procedure described above, (R/S)-4-(2,5-difluorophenyl)fluoromethyl)-piperidine hydrochloride was synthesized.

Reference Q Synthesis of 4-(2,4-difluorophenyl)difluoromethyl)piperidine hydrochloride

Step 1: tert-butyl 4-((2,4-difluorophenyl)difluoromethyl)piperidine-1-carboxylate

To a solution of tert-butyl 4-(2,4-difluorobenzoyl)piperidine-1-carboxylate (7.7 g, 23.67 mmol) in DCM (100 ml) was added DAST (46.9 ml, 355 mmol). The reaction mixture was stirred at reflux for 2 days. Purification by column chromatography afforded the title compound.

Step 2: 4-((2,4-difluorophenyl)difluoromethyl)piperidine hydrochloride

To a solution of tert-butyl 4-((2,4-difluorophenyl)difluoromethyl)piperidine-1-carboxylate (2.6 g, 7.49 mmol) in DCM (10 mL) was added HCl (2.28 mL, 74.9 mmol). The mixture was stirred at −78° C. for 16 h then concentrated under reduced pressure to yield the title compound as a white solid.

Following the procedure described above, following compounds were synthesized using commercially available starting materials.

4-((2,5-difluorophenyl)difluoromethyl)piperidine hydrochloride; and 4-((5-chloro-2-fluorophenyl)difluoromethyl)piperidine hydrochloride.

Reference R Synthesis of 4-fluoro-1-(piperidin-4-ylmethyl)pyridin-2(1H)-one, hydrogen chloride salt

Step 1: tert-butyl 4-((4-fluoro-2-oxopyridin-1(2H)-yl)methyl)piperidine-1-carboxylate

A solution of 4-fluoropyridin-2(1H)-one (112 mg, 0.990 mmol), tert-butyl 4-(bromomethyl)piperidine-1-carboxylate (276 mg, 0.990 mmol) and potassium carbonate (274 mg, 1.981 mmol) in dioxane (1981 μl) was stirred at 80° C. until complete by LCMS analysis. HPLC purification afforded the title compound as a white solid.

Step 2: 4-fluoro-1-(piperidin-4-ylmethyl)pyridin-2(1H)-one, hydrogen chloride salt

A solution of tert-butyl 4-((4-fluoro-2-oxopyridin-1(2H)-yl)methyl)piperidine-1-carboxylate (100 mg, 0.322 mmol) in dioxane (644 μl) was treated with HCl (806 μl, 3.22 mmol, 4 M in dioxane) dropwise via syringe at RT and the resulting reaction mixture stirred for 3 h. The solvent was removed under reduced pressure to yield the title compound as a white solid.

Following the procedure described above, following compounds were synthesized using commercially available pyridinones:

4-chloro-1-(piperidin-4-ylmethyl)pyridin-2(1H)-one hydrochloride; 5-fluoro-1-(piperidin-4-ylmethyl)pyridin-2(1H)-one hydrochloride; and 5-chloro-1-(piperidin-4-ylmethyl)pyridin-2(1H)-one hydrochloride.

Reference S Synthesis of 1-(1-(2,5-dichlorophenyl)ethyl)piperazine hydrochloride

Step 1: tert-butyl 4-(1-(2,5-dichlorophenyl)ethyl)piperazine-1-carboxylate

A 10-mL screwtop vial containing tert-butyl piperazine-1-carboxylate (200 mg, 1.074 mmol), 1-(2,5-dichlorophenyl)ethanone (203 mg, 1.074 mmol), sodium triacetoxyborohydride (341 mg, 1.611 mmol), and acetic acid (92 μl, 1.611 mmol) in DCE (3579 μl) was stirred at RT overnight. 1 M KOH was added with rapid stirring for 30 min, then the reaction mixture was extracted with ether. The combined organic layer was washed with brine and the organic extracts were combined, filtered through MgSO₄, and concentrated to afford the title compound.

Step 2: 1-(1-(2,5-dichlorophenyl)ethyl)piperazine hydrochloride

A 10-mL screwtop vial containing tert-butyl 4-(1-(2,5-dichlorophenyl)ethyl)-piperazine-1-carboxylate (270 mg, 0.751 mmol) and HCl (1879 μl, 7.51 mmol, 4 M in dioxane) in DCM (2505 μl) was stirred overnight and concentrated under reduced pressure to give the title compound.

Reference T Synthesis of N-(4-chlorophenyl)piperidin-4-amine dihydrochloride

Step 1: tert-butyl 4-((4-chlorophenyl)amino)piperidine-1-carboxylate

A 20-mL screwtop vial containing tert-butyl 4-oxopiperidine-1-carboxylate (500 mg, 2.509 mmol), acetic acid (287 μl, 5.02 mmol), and 4-chloroaniline (320 mg, 2.509 mmol) in DCE (6274 μl) was stirred for 10 min then sodium triacetoxyborohydride (745 mg, 3.51 mmol) was added and the reaction mixture was stirred overnight. ISCO purification (0-15% EtOAc/hexanes) afforded the title compound.

Step 2: N-(4-chlorophenyl)piperidin-4-amine dihydrochloride

A 5-mL screwtop vial containing tert-butyl 4-((4-chlorophenyl)amino)piperidine-1-carboxylate (150 mg, 0.483 mmol) was stirred in HCl (965 μl, 3.86 mmol, 4 M in dioxane) overnight. Concentration under reduced pressure gave the title compound.

Reference U Synthesis of N-(2,4-difluorophenyl)piperidin-4-amine bis(2,2,2-trifluoroacetate)

Step 1: tert-butyl 4-((2,4-difluorophenyl)amino)piperidine-1-carboxylate

A 10-mL screwtop vial containing 2,4-difluoroaniline (130 mg, 1.004 mmol), acetic acid (115 μl, 2.008 mmol), and tert-butyl 4-oxopiperidine-1-carboxylate (200 mg, 1.004 mmol) in DCE (2509 μl) was stirred for 10 min and then sodium triacetoxyborohydride (319 mg, 1.506 mmol) was added. After 2 h, the mixture was added to 1 M KOH, then the reaction mixture was extracted with ether. The combined organic layers were washed with brine, filtered through MgSO₄, and concentrated to afford the title compound.

Step 2: N-(2,4-difluorophenyl)piperidin-4-amine bis(2,2,2-trifluoroacetate)

A 50-mL round-bottomed flask containing tert-butyl 4-((2,4-difluorophenyl)amino)piperidine-1-carboxylate (314 mg, 1.005 mmol) in TFA (3 mL) was stirred at RT for 2 h. Concentration under reduced pressure yielded the title compound.

Reference V Synthesis of 7-bromo-2,3-dichloropyrido[3,4-b]pyrazine

Step 1: 7-bromopyrido[3,4-b]pyrazine-2,3(1H,4H)-dione hydrochloride

To a solution of 6-bromopyridine-3,4-diamine (467 mg, 2.484 mmol) in HCl (3726 μl, 14.90 mmol, 4 M aq) was added oxalic acid (257 mg, 2.86 mmol). The mixture was heated at 120° C. for 14 h then filtered, washed with cold water and dried under vacuum to yield the title compound as a tan solid.

Step 2: 7-bromo-2,3-dichloropyrido[3,4-b]pyrazine

To 7-bromopyrido[3,4-b]pyrazine-2,3(1H,4H)-dione hydrochloride (626 mg, 2.248 mmol) was added thionyl chloride (6070 μl, 83 mmol) and N,N-dimethylformamide (174 μl, 2.248 mmol). The reaction mixture was heated at 80° C. overnight then poured into ice water and filtered. The solid was dried under vacuum for 2 h to give the title compound as a pale solid that was used without further purification.

Reference W Synthesis of 2,3,7-trichloropyrido[3,4-b]pyrazine

Step 1: 7-bromopyrido[3,4-b]pyrazine-2,3 (1H,4H)-dione hydrochloride

To a solution of 6-bromopyridine-3,4-diamine (467 mg, 2.484 mmol) in HCl (3726 μl, 14.90 mmol, 4 M aq) was added oxalic acid (257 mg, 2.86 mmol). The mixture was heated at 120° C. for 14 h then filtered, washed with cold water and dried under vacuum to yield the title compound as a tan solid.

Step 2: 2,3,7-trichloropyrido[3,4-b]pyrazine

To 7-bromopyrido[3,4-b]pyrazine-2,3(1H,4H)-dione hydrochloride (130 mg, 0.467 mmol) was added POCl₃ (1305 μl, 14.00 mmol) and N,N-dimethylformamide (36.1 μl, 0.467 mmol). The mixture was heated at 120° C. for 16 h then poured into ice water. The mixture was extracted with EtOAc, washed with water, dried over Na₂SO₄ and concentrated under reduced pressure. The crude material was dried under vacuum then used directly without further purification.

Reference X Synthesis of 2-(cyclopropylamino)-3-(piperidin-4-yl)quinoxaline-6-carbonitrile

Step 1: tert-butyl 4-(7-cyano-3-(cyclopropylamino)quinoxalin-2-yl)-5,6-dihydropyridine-1(2H)-carboxylate

A 10 mL microwave vial containing 3-chloro-2-(cyclopropylamino)quinoxaline-6-carbonitrile (200 mg, 0.817 mmol), tert-butyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-5,6-dihydropyridine-1(2H)-carboxylate (455 mg, 1.471 mmol), bis(triphenylphosphine)palladium(II) chloride (115 mg, 0.163 mmol), and potassium carbonate (339 mg, 2.452 mmol) in MeCN (4087 μl) was degassed with nitrogen for 10 min then heated to 150° C. for 1 h. Concentration under reduced pressure and ISCO purification (35% EtOAc/hexanes) gave the title compound.

Step 2: 2-(cyclopropylamino)-3-(1,2,3,6-tetrahydropyridin-4-yl)quinoxaline-6-carbonitrile dihydrochloride

A 5 mL screwtop-vial containing tert-butyl 4-(7-cyano-3-(cyclopropylamino)quinoxalin-2-yl)-5,6-dihydropyridine-1(2H)-carboxylate (220 mg, 0.562 mmol) and HCl (2810 μl, 11.24 mmol, 4 M in dioxane) in CH₂Cl₂ (Volume: 562 μl) was stirred overnight and concentrated to yield the title compound.

Step 3: 2-(cyclopropylamino)-3-(piperidin-4-yl)quinoxaline-6-carbonitrile

To a 5 mL screw-top vial containing 2-(cyclopropylamino)-3-(1,2,3,6-tetrahydropyridin-4-yl)quinoxaline-6-carbonitrile dihydrochloride (18 mg, 0.049 mmol) and 10% palladium on carbon (5.26 mg, 0.049 mmol) in methanol (247 μl) was bubbled hydrogen under balloon pressure for 30 min. Filtration, concentration, and HPLC purification gave the title compound.

Reference Y Synthesis of N-cyclopropyl-7-methyl-3-(piperidin-4-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt

Step 1: tert-butyl 4-(2-(cyclopropylamino)-7-methylpyrido[3,4-b]pyrazin-3-yl)-5,6-dihydropyridine-1(2H)-carboxylate

A vial charged with 3-chloro-N-cyclopropyl-7-methylpyrido[3,4-b]pyrazin-2-amine (50 mg, 0.213 mmol), tert-butyl 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)-5,6-dihydropyridine-1(2H)-carboxylate (119 mg, 0.383 mmol), potassium carbonate (88 mg, 0.639 mmol) and Pd(PPh₃)₂Cl₂ (29.9 mg, 0.043 mmol), was evacuated/refilled with nitrogen (3×). MeCN (1065 μl) was added to the reaction mixture and the vial was evacuated and refilled with nitrogen (3×). The resulting mixture was heated at 80° C. overnight. ISCO purification (0-5% MeOH/DCM) gave the title compound as an off-white solid.

Step 2: tert-butyl 4-(2-(cyclopropylamino)-7-methylpyrido[3,4-b]pyrazin-3-yl)piperidine-1-carboxylate, 2,2,2-trifluoroacetic acid salt

A mixture of tert-butyl 4-(2-(cyclopropylamino)-7-methylpyrido[3,4-b]pyrazin-3-yl)-5,6-dihydropyridine-1(2H)-carboxylate (30 mg, 0.079 mmol) and 10% palladium on carbon (3 mg, 2.82 μmol) in MeOH (393 μl) was stirred under a hydrogen balloon at RT overnight. HPLC purification gave the title compound as an off-white solid.

Step 3: N-cyclopropyl-7-methyl-3-(piperidin-4-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt

To a solution of tert-butyl 4-(2-(cyclopropylamino)-7-methylpyrido[3,4-b]pyrazin-3-yl)piperidine-1-carboxylate 2,2,2-trifluoroacetate (18 mg, 0.036 mmol) in DCM (0.3 ml) at 0° C. was added TFA (0.15 ml). The resulting solution was stirred at 0° C. for 2 h and then concentrated under reduced pressure to yield the title compound as a colorless oil.

Reference Z Synthesis of N-cyclopropyl-3-(3-methylpiperazin-1-yl)quinoxalin-2-amine dihydrochloride

Step 1: tert-butyl 4-(3-(cyclopropylamino)quinoxalin-2-yl)-2-methylpiperazine-1-carboxylate

To a solution of 3-chloro-N-cyclopropylquinoxalin-2-amine (100 mg, 0.455 mmol) in dioxane (455 μl) was added tert-butyl 2-methylpiperazine-1-carboxylate (137 mg, 0.683 mmol) and iPr₂EtN (119 μl, 0.683 mmol). The mixture was heated at 130° C. for 60 h. Purification by ISCO (0-60% EtOAc/Hexanes) yielded the title compound as a yellow oil.

Step 2: N-cyclopropyl-3-(3-methylpiperazin-1-yl)quinoxalin-2-amine dihydrochloride

To a solution of tert-butyl 4-(3-(cyclopropylamino)quinoxalin-2-yl)-2-methylpiperazine-1-carboxylate (177 mg, 0.462 mmol) in dioxane (1539 μl) was added HCl (346 μl, 1.385 mmol, 4 M in dioxane). The mixture was heated at 75° C. for 20 h. The solvent was removed under reduced pressure to yield the title compound as a tan solid.

Synthesized by a similar procedure, using commercially available Boc-piperazines:

methyl 4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazine-2-carboxylate dihydrochloride; N-cyclopropyl-3-(3-(methoxymethyl)piperazin-1-yl)quinoxalin-2-amine dihydrochloride; N-cyclopropyl-3-(3-isopropylpiperazin-1-yl)quinoxalin-2-amine dihydrochloride; N-cyclopropyl-3-(2-methylpiperazin-1-yl)quinoxalin-2-amine dihydrochloride; 3-(3-benzylpiperazin-1-yl)-N-cyclopropylquinoxalin-2-amine dihydrochloride

Reference AA Synthesis of 1-(4-(piperidin-4-yloxy)phenyl)ethanone, hydrogen chloride salt

Step 1: tert-butyl 4-(4-acetylphenoxyl)piperidine-1-carboxylate

To a 20 mL screwtop vial containing tert-butyl 4-hydroxypiperidine-1-carboxylate (500 mg, 2.484 mmol), 1-(4-hydroxyphenyl)ethanone (372 mg, 2.73 mmol), and triphenylphosphine (782 mg, 2.98 mmol) in THF (8281 μl) was added DEAD (1475 μl, 3.73 mmol) dropwise and heated to 50° C. for 4 h. ISCO purification (0-100% hexanes/ethyl acetate) gave the title compound.

Step 2: 1-(4-(piperidin-4-yloxy)phenyl)ethanone, hydrogen chloride salt

To a 10 mL screwtop vial containing tert-butyl 4-(4-acetylphenoxyl)piperidine-1-carboxylate (580 mg, 1.816 mmol) and HCl (2270 μl, 9.08 mmol, 4 M in dioxane) in dioxane (3632 μl) was stirred for 2 h and concentrated to yield the title compound as a white solid.

Synthesized by a similar procedure, using commercially available phenols: N,N-dimethyl-4-(piperidin-4-yloxy)benzamide, hydrogen chloride salt; 4-(4-(methylthio)phenoxy)piperidine, hydrogen chloride salt; 4-(4-ethoxyphenoxyl)piperidine, hydrogen chloride salt

Reference AB Synthesis of (2-fluoro-5-(methylthio)phenyl)(piperidin-4-yl)methanone, hydrogen chloride salt

Step 1: tert-butyl 4-(2-fluoro-5-(methylthio)benzoyl)piperidine-1-carboxylate

To a 50 mL round-bottomed flask containing (3-bromo-4-fluorophenyl)(methyl)sulfane (250 mg, 1.131 mmol) in THF (5654 μl) at −78° C. was added tert-butyllithium (1397 μl, 2.375 mmol) dropwise by syring-pump. After 10 min, tert-butyl 4-(methoxy(methyl)carbamoyl)piperidine-1-carboxylate (339 mg, 1.244 mmol) was added and the reaction mixture was warmed to RT then quenched with AcOH. ISCO purification (20% ethyl acetate in hexanes) gave the title compound.

Step 2: (2-fluoro-5-(methylthio)phenyl)(piperidin-4-yl)methanone, hydrogen chloride salt

A 5 mL screwtop vial containing tert-butyl 4-(2-fluoro-5-(methylthio)benzoyl)piperidine-1-carboxylate (200 mg, 0.566 mmol) and HCl (2.122 mL, 8.49 mmol, 4 M in dioxane) in dioxane (1.132 mL) was stirred overnight. Concentration in vacuo yielded the title compound as a white solid. Synthesized by a similar procedure, using commercially available aryl bromides: 3-fluoro-4-(piperidin-4-yloxy)phenol, hydrogen chloride salt

Reference AC Synthesis of 4-(2-fluoro-4-(2-fluoroethoxyl)phenoxy)piperidine, hydrogen chloride salt

Step 1: tert-butyl 4-(2-fluoro-4-(2-fluoroethoxyl)phenoxy)piperidine-1-carboxylate

A 5 mL screwtop vial containing tert-butyl 4-(2-fluoro-4-hydroxyphenoxy)piperidine-1-carboxylate (42 mg, 0.135 mmol) and sodium hydride (4.86 mg, 0.202 mmol, 60% dispersion in mineral oil) in DMF (674 μl) was stirred for 10 min then added 1-bromo-2-fluoroethane (30.2 μl, 0.405 mmol). After 2 h the reaction mixture was poured into water, extracted with ether (2×) and filtered through MgSO4, Concentration in vacuo yielded the title compound.

Step 2: 4-(2-fluoro-4-(2-fluoroethoxyl)phenoxy)piperidine, hydrogen chloride salt

A 5 mL screwtop vial containing tert-butyl 4-(2-fluoro-4-(2-fluoroethoxyl)phenoxy)piperidine-1-carboxylate (45 mg, 0.126 mmol) and HCl (472 μl, 1.889 mmol, 4 M in dioxane) in dioxane (252 μl) was stirred overnight then concentrated to give the title compound.

Reference AD Synthesis of 5-chloro-N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine

Step 1: 5-bromopyrido[3,4-b]pyrazine-2,3(1H,4H)-dione

A solution of 1,2-di(1H-imidazol-1-yl)ethane-1,2-dione (1.456 g, 7.66 mmol) and 2-bromopyridine-3,4-diamine (1.2 g, 6.38 mmol) in DMF (21.27 ml) was stirred at RT overnight. The precipitate was filtered and washed with anhydrous THF to give the title compound as a grey solid.

Step 2: 2,3,5-trichloropyrido[3,4-b]pyrazine

To a flask containing 5-bromopyrido[3,4-b]pyrazine-2,3(1H,4H)-dione (1.5 g, 6.20 mmol) was added sulfurous dichloride (16.74 ml, 229 mmol) and N,N-dimethylformamide (0.480 ml, 6.20 mmol). The mixture was heated at 78° C. overnight then water was added to quench the reaction. Filtration afforded the title compound as a light yellow solid.

Step 3: 3,5-dichloro-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine

To a solution of 2,3,5-trichloropyrido[3,4-b]pyrazine (600 mg, 2.56 mmol) in DCM (12.8 mL) at 0° C. was slowly added N-ethyl-N-isopropylpropan-2-amine (1341 μl, 7.68 mmol) and cyclopropanamine (248 μl, 3.58 mmol). The reaction was stirred at 0° C. for 3 h. ISCO purification (0-100% EtOAc in hexanes) yielded the title compound as a white solid.

Step 4: 5-chloro-N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine

A solution of 3,5-dichloro-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine (57 mg, 0.223 mmol), 4-(2-fluoro-4-methoxyphenoxy)piperidine, HCl (76 mg, 0.290 mmol, 4 M in dioxane) and N-ethyl-N-isopropylpropan-2-amine (156 μl, 0.894 mmol) in dioxane (745 μl) was heated at 60° C. for 2 h. ISCO purification (10-60% ethyl acetate in hexanes) gave the title compound as a white solid.

Synthesized by a similar procedure, using reference compound piperizines: 5-chloro-N-cyclopropyl-3-(4-(2,4-difluorophenoxyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine; 5-chloro-N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine

Reference AF Synthesis of (5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazine-2,3-diyl)dimethanol

Step 1: 5,6-dichloropyrazine-2,3-dicarboxylic acid dihydrochloride

A suspension of 2,3-dichloroquinoxaline (10 g, 50.2 mmol) in H₂O (500 mL) was heated to 95° C. with stirring and KMnO₄ (39.7 g, 251 mmol) in hot H₂O (600 mL) was added dropwise over 2 h. The reaction continued stirring for another 2 h, and then the solid MnO2 was removed by filtration from the hot suspension and washed twice with hot H₂O. The combined filtrate was concentrated to 100 mL, cooled to 0° C., and acidified with cold conc. HCl (pH<0). Filtration afforded the title compound as a colorless solid.

Step 2: dimethyl 5,6-dichloropyrazine-2,3-dicarboxylate

To a suspension of 5,6-dichloropyrazine-2,3-dicarboxylic acid dihydrochloride (310 mg, 1.000 mmol) in MeOH (3 ml) was added SOCl₂ (0.584 ml, 8.00 mmol), dropwise, at 0° C. The reaction mixture was allowed to stir at 60° C. for 3 h and was then concentrated to dryness. EtOAc was added and the suspension was filtered. The filtrate was concentrated in vacuo and purified by column chromatograph (petroleum ether in ethyl acetate=20:1, then 15:1) to give the title compound as a solid.

Step 3: dimethyl 5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazine-2,3-dicarboxylate

A solution of dimethyl 5,6-dichloropyrazine-2,3-dicarboxylate (2 g, 7.55 mmol) in dioxane (7.55 ml) and DMF (7.55 ml) was treated with propan-2-amine (0.643 ml, 7.55 mmol) and DIPEA (3.29 ml, 18.86 mmol) and then stirred at RT overnight. Then, 4-(2,4-difluorophenoxyl)piperidine hydrochloride (1.884 g, 7.55 mmol), and DIPEA (3.29 ml, 18.86 mmol) were added and the resulting reaction mixture stirred at 90° C. for 8 h. ISCO purification gave dimethyl the title compound as a white solid.

Step 4: (5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazine-2,3-diyl)dimethanol

To a solution of dimethyl 5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazine-2,3-dicarboxylate (2 g, 4.31 mmol) in THF (43.1 ml) at 0° C. was added Super-hydride (21.53 ml, 21.53 mmol) and the reaction was stirred at RT for 2 h. Then, the reaction was quenched with 1N HCl (pH=2-4). Saturated NaHCO₃ was added to adjust the pH to 8 and then the reaction mixture was extracted with ethyl acetate (30 mL×2). ISCO purification (10-80% ethyl acetate in hexanes) gave the title compound as a colorless oil.

Example 1 Synthesis of N-cyclopropyl-3-(4-(3-methylbenzyl)piperazin-1-yl)naphthalen-2-amine

A solution of 3-chloro-N-cyclopropylquinoxalin-2-amine (30 mg, 0.137 mmol), 1-(3-methylbenzyl)piperazine (39.0 mg, 0.205 mmol) and N-ethyl-N-isopropylpropan-2-amine (0.072 ml, 0.410 mmol) in dioxane (0.25 ml) was heated at 150° C. overnight. HPLC purification afforded the title compound as a white solid. MS (ESI, pos. ion) m/z: 374.3 (M+1)

Using similar reaction conditions as described above, and utilizing intermediates prepared as described above or commercially available piperazines and piperidines, following compounds were synthesized which were purified by either HPLC or ISCO:

N-cyclopropyl-3-(4-(3-methylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(3-(thiazol-5-ylmethyl)piperidin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 5-bromo-N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine; 8-bromo-N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-2-(4-(3-methylbenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-2-(4-(2,5-dichlorobenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; 7-bromo-N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 6-bromo-N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; mixture of N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-7-methoxyquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt and N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-7-methoxyquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; mixture of N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-7-fluoroquinoxalin-2-amine and N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-7-fluoroquinoxalin-2-amine; 2-(cyclopropylamino)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2-methoxyphenyl)quinoxalin-2-amine; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(4-fluorophenyl)quinoxalin-2-amine; N-(4-bromophenyl)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine; N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-5,7-dimethylquinoxalin-2-amine; N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-6,8-dimethylquinoxalin-2-amine; 8-bromo-N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (4-chlorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone; N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(2,6-dichlorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile; 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile; N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 7-bromo-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 7-chloro-N-cyclopropyl-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 7-chloro-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile; 2-((2,2-difluoroethyl)amino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile; 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile; 2-((2,2-difluoroethyl)amino)-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)quinoxaline-6-carbonitrile; 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-2-((2-methoxyethyl)amino)quinoxaline-6-carbonitrile; 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-N-(2-methoxyethyl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-N-(2-methoxyethyl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N-(2-methoxyethyl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-2-((2-methoxyethyl)amino)quinoxaline-6-carbonitrile; 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-2-((2-methoxyethyl)amino)quinoxaline-6-carbonitrile; 3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-((2-methoxyethyl)amino)quinoxaline-6-carbonitrile; 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-(2-methoxyethyl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4((2,4-difluorophenyl)difluoromethyl)piperidin-1-yl)-5-methylpyrido[3,4-b]pyrazin-2-amine; 2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)difluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile; N-cyclopropyl-3-(4-((2,4-difluorophenyl)difluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine; N-cyclopropyl-3-(4-phenoxypiperidin-1-yl)quinoxalin-2-amine; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)quinoxalin-2-amine; 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((6-methoxypyridin-3-yl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-N-(2,2-difluoroethyl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-N-(2,2-difluoroethyl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (4-chloro-2-fluorophenyl)(4-(2-((2,2-difluoroethyl)amino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; N-(2,2-difluoroethyl)-3-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(pyridin-3-ylamino)-3-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chloro-2-fluorobenzoyl)piperazin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-2-(pyridin-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-chlorophenoxyl)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2-fluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(3-fluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(4-fluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(4-fluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(3,4-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-((4-fluorophenyl)sulfonyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chlorobenzyl)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chlorophenoxyl)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chlorophenoxyl)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (4-chlorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(3-(4-fluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,5-difluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4,6-trifluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(4-fluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2-fluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,5-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(4-(5-chloro-2-fluorophenoxy)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-phenoxypiperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,4-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,4,6-trifluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-chloro-2,6-difluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-chloro-2-fluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, 2,2,2-trifluoroacetic acid salt; (5-chloro-2-fluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-N-cyclopropyl-7-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(5-chloro-2-fluorobenzoyl)piperidin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-6,7-difluoroquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-6-fluoroquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(cyclopropylamino)-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-((2,4-difluorophenyl)-fluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-5-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-5-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-5-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-5-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-(cyclobutylamino)quinoxaline-6-carbonitrile; 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile; N-cyclopropyl-3-(4-(1-(2,5-dichlorophenyl)ethyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-((4-chlorophenyl)amino)piperidin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-((2,4-difluorophenyl)amino)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3-(trifluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-(methylsulfonyl)phenyl)methanone, 22,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,5-dichlorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3,4-dichlorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (3-chloro-4-methoxyphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3,5-dichlorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (3-chlorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(pyridin-3-ylmethyl)piperazin-1-yl)quinoxalin-2-amine, 22,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,3-dichlorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-((5-methyloxazol-2-yl)methyl)piperidin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(pyridin-4-ylmethyl)piperazin-1-yl)quinoxalin-2-amine, 22,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-((3-methyl-1,2,4-oxadiazol-5-yl)methyl)piperidin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(pyridin-2-ylmethyl)piperazin-1-yl)quinoxalin-2-amine, 22,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-(trifluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,6-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-bromobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(3-methoxypropyl)quinoxalin-2-amine; (2-chloro-4-(methylsulfonyl)phenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3,6-dichloropyridin-2-yl)methanone; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(5-methylisoxazol-3-yl)methanone; (4-chlorophenyl)(4-(3-(cyclopropylamino)-6,7-difluoroquinoxalin-2-yl)piperazin-1-yl)methanone; (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(4-(trifluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(4-(5-chloro-2-(difluoromethoxy)benzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(4-fluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,6-dichlorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,5-dimethylbenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)-7-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,5-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile; 2-(cyclobutylamino)-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)quinoxaline-6-carbonitrile; 2-(cyclopropylamino)-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((4-fluoro-2-oxopyridin-1(2H)-yl)methyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(2,5-difluorobenzoyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 1-((1-(2-(cyclopropylamino)-7-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)-4-fluoropyridin-2(1H)-one, 2,2,2-trifluoroacetic acid salt; 2-(cyclobutylamino)-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(cyclopropylamino)-2-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 8-chloro-N-cyclopropyl-3-(4-((2,5-difluorophenyl)-fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 6-bromo-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-2-((3,3,3-trifluoropropyl)-amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((2,5-difluorophenyl)-fluoromethyl)piperidin-1-yl)-2-((3,3,3-trifluoropropyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-2-((3,3,3-trifluoropropyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((3,3,3-trifluoropropyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-2-((3,3,3-trifluoropropyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 6-bromo-N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 6-bromo-3-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 6-bromo-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 6-bromo-N-cyclopropyl-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 6-bromo-N-cyclopropyl-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 7-bromo-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 7-bromo-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)-piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-((4-chloro-2-oxopyridin-1(2H)-yl)methyl)piperidin-1-yl)-2-(cyclopropylamino)-quinoxaline-6-carbonitrile; 1-((1-(2-(cyclopropylamino)-5-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)-5-fluoropyridin-2(1H)-one; 4-chloro-1-((1-(2-(cyclopropylamino)-5-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)pyridin-2(1H)-one; 2-(cyclopropylamino)-3-(4-((5-fluoro-2-oxopyridin-1(2H)-yl)methyl)piperidin-1-yl)quinoxaline-6-carbonitrile; 1-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)-4-fluoropyridin-2(1H)-one; 1-((1-(2-(cyclopropylamino)-5-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)-4-fluoropyridin-2(1H)-one; 5-chloro-1-((1-(2-(cyclopropylamino)-pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)pyridin-2(1H)-one; 3-(4-((5-chloro-2-fluorophenyl)difluoromethyl)piperidin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile; 3-(4-((5-chloro-2-fluorophenyl)difluoromethyl)piperidin-1-yl)-N-cyclopropyl-7-methylpyrido[3,4-b]pyrazin-2-amine; 3-(4-((5-chloro-2-oxopyridin-1(2H)-yl)methyl)piperidin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile; 3-(4-((5-chloro-2-fluorophenyl)difluoromethyl)piperidin-1-yl)-N-cyclopropyl-5-methylpyrido[3,4-b]pyrazin-2-amine; 5-chloro-1-((1-(2-(cyclopropylamino)-5-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)pyridin-2(1H)-one; 5-chloro-1-((1-(2-(cyclopropylamino)-7-methylpyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methyl)pyridin-2(1H)-one; 3-(4-((5-chloro-2-fluorophenyl)difluoromethyl)-piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine; N-cyclopropyl-3-(4-((2,5-difluorophenyl)difluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine; N-cyclopropyl-3-(4-((2,5-difluorophenyl)difluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine; N-cyclopropyl-3-(4-((2,5-difluorophenyl)-difluoromethyl)piperidin-1-yl)-5-methylpyrido[3,4-b]pyrazin-2-amine; 2-(cyclopropylamino)-3-(4-((2,5-difluorophenyl)difluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile, and 7-chloro-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine; N-cyclopropyl-3-(4-(pyridin-3-yloxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine; N-cyclopropyl-3-(4-(4-methoxyphenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine; N-cyclopropyl-3-(4-(pyridin-2-yloxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine; N-cyclopropyl-3-(4-(pyridin-4-yloxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2-methoxyphenyl)methanone, 2,2,2-trifluoroacetic acid salt; 4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)benzonitrile; (2-chlorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(3-methoxyphenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2-methoxyphenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(phenyl)methanone; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,3-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (3-chlorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone; 3-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)benzonitrile; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(3-methoxyphenyl)methanone; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(o-tolyl)methanone, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,6-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (2-chloro-5-fluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(3-fluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; 1-(4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)phenyl)ethanone, 2,2,2-trifluoroacetic acid salt; 4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)-N,N-dimethylbenzamide, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(4-(methylthio)phenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2-fluoro-5-(methylthio)phenyl)methanone, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(4-ethoxyphenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2-fluoro-4-(2-fluoroethoxyl)phenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)-3-fluorophenol, 2,2,2-trifluoroacetic acid salt; (6-chloro-2,3-difluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (2-chloro-3-fluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, hydrogen chloride salt; (2-chlorothiophen-3-yl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, hydrogen chloride salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(thiophen-2-yl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidine-4-carbonyl)benzonitrile, hydrogen chloride salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2-(methylthio)phenyl)methanone, 2,2,2-trifluoroacetic acid salt; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(thiophen-3-yl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidine-4-carbonyl)-4-fluorobenzonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-ethyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 2-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)benzonitrile; (2-chloro-6-fluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone; (2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-((4-fluorophenyl)sulfonyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine 2,2,2-trifluoroacetate

Example 2 Synthesis of 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyrazin-2-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt

3-Chloro-N-(pyrazin-2-yl)quinoxalin-2-amine (210 mg, 0.815 mmol) and 1-(2,5-dichlorobenzyl)piperazine (220 mg, 0.896 mmol) were added to n-BuOH (0.8 ml). After stirring for 2 h at 90° C., the reaction mixture was purified by HPLC to yield the title compound as a yellow solid. MS (ESI, pos. ion) m/z: 466.0 (M+1)

Utilizing similar reaction conditions as described above, following compounds were synthesized:

3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyrimidin-4-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyridazin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(1,2,4-triazin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(5,6-dimethyl-1,2,4-triazin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-(3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-yl)-3,4-dimethylisoxazol-5-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyridin-4-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyridin-2-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2,2,2-trifluoroethyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; and 2-(cyclobutylamino)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt.

Example 3 Synthesis of 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-((2-fluoroethyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt

A suspension of 3-chloro-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile (50 mg, 0.186 mmol), (4-chlorophenyl)(piperazin-1-yl)methanone hydrochloride (72.9 mg, 0.279 mmol) and DIPEA (0.098 ml, 0.558 mmol) in DMSO (1 ml) was stirred at RT for 16 h. After HPLC purification, most of MeCN was removed under reduced pressure. The resulting suspension was neutralized with solid Na₂CO₃ and extracted with EtOAc. The organic layer was dried over Na₂SO₄ and concentrated to afford the title compound as a yellow solid. MS (ESI, pos. ion) m/z: 438.8 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized:

3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile; 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-(isoxazol-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-(isoxazol-3-ylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-((2-fluoroethyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((2-fluoroethyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-((2,2-difluoroethyl)amino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-(isoxazol-3-ylamino)quinoxaline-6-carbonitrile.

Example 4 Synthesis of benzofuran-3-yl(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone

To a 1-dram vial was added benzofuran-3-carboxylic acid (11.84 mg, 0.073 mmol), HATU (27.8 mg, 0.073 mmol), and iPr₂EtN (44.7 μl, 0.256 mmol) in DMF (365 μl). After stirring at RT for 30 min, N-cyclopropyl-3-(piperazin-1-yl)quinoxalin-2-amine, 2HCl (25 mg, 0.073 mmol) was added. The reaction mixture was stirred for 3 h and then HPLC purification yielded the title compound as a colorless oil. MS (ESI, pos. ion) m/z: 414.3 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized:

(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3,4-dimethylphenyl-)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,4-dichlorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; 4-(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazine-1-carbonyl)benzonitrile, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-ethylphenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,5-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)-quinoxalin-2-yl)piperazin-1-yl)(naphthalen-2-yl)methanone, 2,2,2-trifluoroacetic acid salt; (2-bromo-5-methoxyphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (3-bromo-4-methoxyphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-bromo-2-chlorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(5-fluoro-2-methylphenyl)methanone, 2,2,2-trifluoroacetic acid salt; (3-bromo-4-fluorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-bromo-2-fluorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (5-bromo-2-fluorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-ethoxyphenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3-isopropylphenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)-quinoxalin-2-yl)piperazin-1-yl)(4-isopropylphenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-bromo-2-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (2-chloro-3,6-difluorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (2-chloro-5-iodophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (5-bromo-2-methylphenyl)(4-(3-(cyclopropylamino)-quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-(trifluoromethoxy)phenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(1H-indol-6-yl)methanone, 2,2,2-trifluoroacetic acid salt; (5-chloro-2-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-chloro-2-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,4-dimethylphenyl)methanone, 2,2,2-trifluoroacetic acid salt; (2-chloro-5-methoxyphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; 5-(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazine-1-carbonyl)-2-isopropoxybenzonitrile, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2-methoxy-5-(trifluoromethoxy)phenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,3,5-trichlorophenyl)-methanone, 2,2,2-trifluoroacetic acid salt; (2-chloro-6-(trifluoromethyl)phenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(chloromethyl)phenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(1H-indol-5-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-bromo-3-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-fluoro-3-methoxyphenyl)methanone, 2,2,2-trifluoroacetic acid salt; (3-bromo-4-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-chloro-3-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(4-fluoro-2-methylphenyl)methanone; (3-bromo-2-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3,5-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-bromophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-(cyclopropylamino)-quinoxalin-2-yl)piperazine-1-carbonyl)benzonitrile, 2,2,2-trifluoroacetic acid salt; (3-bromophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,6-dichlorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (2-bromo-4-methylphenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; 4-(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazine-1-carbonyl)-3-fluorobenzonitrile, 2,2,2-trifluoroacetic acid salt; benzo[d][1,2,3]thiadiazol-5-yl(4-(3-(cyclopropylamino)-quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (2-chloro-5-fluorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2-methoxy-5-(trifluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-bromo-3-(trifluoromethyl)phenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone; (4-chloro-3-methylphenyl)(4-(3-(pyridin-3-ylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (3-bromo-4-fluorophenyl)(4-(3-(cyclopropylamino)-6,7-difluoroquinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-bromo-4-fluorobenzoyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-bromo-4-fluorobenzoyl)piperazin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-bromo-4-fluorobenzoyl)piperazin-1-yl)-2-(cyclobutylamino)-quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; (4-chlorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (2-chlorophenyl)(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(m-tolyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,5-dichlorothiophen-3-yl)methanone; (4-(2-(cyclopropylamino)pyrido-[3,4-b]pyrazin-3-yl)piperazin-1-yl)(4-(difluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-chloro-3-fluorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(3,4-difluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (3-chloro-4-fluorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-chloro-2-fluorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (2-chloro-4-fluorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-chloro-2-hydroxyphenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-chloro-2-methoxyphenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(1-(4-chlorobenzoyl)piperidin-4-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopropylamino)quinoxalin-2-yl)-3-methylpiperazin-1-yl)(2,5-dichlorophenyl)methanone, 2,2,2-trifluoroacetic acid salt.

Example 5 Synthesis of cyclohexyl(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone

A solution of N-cyclopropyl-3-(piperazin-1-yl)quinoxalin-2-amine dihydrochloride (50 mg, 0.146 mmol) and Et₃N (30.5 μl, 0.219 mmol) in DCM (365 μl) was treated with cyclohexanecarbonyl chloride (23.93 μl, 0.175 mmol) dropwise via syringe at RT. The resulting reaction mixture was stirred for 2 h. ISCO purification (40% EtOAc/Hexanes) afforded the title compound as a light-yellow solid. MS (ESI, pos. ion) m/z: 380.3 (M+1)

Example 6 Synthesis of 3-(4-(4-chlorobenzoyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile

To a solution of 4-chlorobenzoic acid (6.39 mg, 0.041 mmol) in CH₂Cl₂ (136 μl) was added 3 drops DMF and oxalyl chloride (5.36 μl, 0.061 mmol). The reaction mixture was allowed to stir at RT for 60 min then added to a solution of 2-(cyclopropylamino)-3-(piperazin-1-yl)quinoxaline-6-carbonitrile, 2HCl (15 mg, 0.041 mmol) and triethylamine (19.92 μl, 0.143 mmol) in CH₂Cl₂ (200 μl). The reaction mixture was allowed to stir at RT for 2 h. ISCO purification (0-100% EtOAc/Hexanes) yielded the title compound as a yellow oil. MS (ESI, pos. ion) m/z: 433.3 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized:

(4-chlorophenyl)(4-(3-(cyclopropylamino)-7-fluoroquinoxalin-2-yl)piperazin-1-yl)methanone; (4-chlorophenyl)(4-(3-(pyridin-3-ylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-bromo-3-fluorophenyl)(4-(3-(cyclopropylamino)-7-fluoroquinoxalin-2-yl)piperazin-1-yl)methanone; 2-(cyclopropylamino)-3-(4-(2,5-dichloroisonicotinoyl)piperazin-1-yl)quinoxaline-6-carbonitrile; 2-(cyclopropylamino)-3-(4-(2,5-dichloronicotinoyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(2-fluoro-4-(trifluoromethyl)phenyl)methanone, 2,2,2-trifluoroacetic acid salt; (5-chloro-3-fluoropyridin-2-yl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(2-(cyclopropylamino)-pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(2-fluoro-4-methylphenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(2-fluoro-4-methoxyphenyl)methanone, 2,2,2-trifluoroacetic acid salt; (4-chloro-2-methylphenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; 4-(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazine-1-carbonyl)-3-fluorobenzonitrile, 2,2,2-trifluoroacetic acid salt; (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(4-fluoro-2-hydroxyphenyl)-methanone, 2,2,2-trifluoroacetic acid salt; (4-chloro-2,6-difluorophenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(3-fluoropyridin-2-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-chloro-2-(trifluoromethyl)phenyl)(4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; (4-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(2,4,6-trifluorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; and (4-(2-(cyclopropylamino)-pyrido[3,4-b]pyrazin-3-yl)piperazin-1-yl)(2,4-difluoro-6-hydroxyphenyl)methanone, 2,2,2-trifluoroacetic acid salt.

Example 7 Synthesis of 3-(4-(benzofuran-3-ylmethyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine

To a solution of benzofuran-3-yl(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, TFA (8 mg, 0.015 mmol) in THF (152 μl) was added triethylamine (2.114 μl, 0.015 mmol). The mixture was cooled to 0° C. and BH₃-THF (76 μl, 0.076 mmol, 1 M in THF) was added. The reaction mixture was stirred at RT for 18 h. ISCO purification (0-60% EtOAc/Hexanes) yielded the title compound as a yellow oil. MS (ESI, pos. ion) m/z: 400.3 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized:

N-cyclopropyl-3-(4-((2,5-dichlorothiophen-3-yl)methyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-((3,6-dichloropyridin-2-yl)methyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(cyclohexylmethyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine; 3-(4-(2-chloro-4-(methylsulfonyl)benzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-((5-methylisoxazol-3-yl)methyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; and 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-cyclopropyl-6,7-difluoroquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt.

Example 8 Synthesis of N-cyclopropyl-3-(4-(5-fluoro-2-methylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt

To a solution of (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(5-fluoro-2-methylphenyl)methanone 2,2,2-trifluoroacetate (65 mg, 0.125 mmol) in THF (1 ml) was added diisobutylaluminum hydride (142 mg, 1.001 mmol, 1 M in hexanes) at RT. The reaction mixture was stirred at RT for 16 h. HPLC purification afforded the title compound as a white solid. MS (ESI, pos. ion) m/z: 391.9 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized:

N-cyclopropyl-3-(4-(4-fluoro-2-methylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chloro-3-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-bromo-5-methoxybenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-bromo-4-methoxybenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-bromo-2-chlorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-bromo-4-fluorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-bromo-2-fluorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(5-bromo-2-fluorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(5-bromo-2-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-((1H-indol-6-yl)methyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(5-chloro-2-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chloro-2-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-chloro-3,6-difluorobenzyl)-piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-chloro-5-methoxybenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-chloro-6-(trifluoromethyl)benzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(3-isopropylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chloro-4-methoxybenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-bromo-3-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-bromo-2-methylbenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-chloro-5-iodobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2-methoxy-5-(trifluoromethoxy)benzyl)-piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,3,5-trichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-((2-chloro-5-fluoropyridin-3-yl)methyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-bromo-5-chlorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(5-chloro-2-(trifluoromethyl)-benzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,6-difluoro-3-methylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; and N-cyclopropyl-3-(4-(2-methoxy-5-(trifluoromethyl)benzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt.

Example 9 Synthesis of N-cyclopentyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine

A solution of (4-(3-(cyclopentylamino)quinoxalin-2-yl)piperazin-1-yl)(2,5-dichlorophenyl)methanone (16 mg, 0.034 mmol) in THF (0.35 mL) and DCM (0.35 mL) was added trifluoromethanesulfonic acid anhydride (0.017 mL, 0.102 mmol) at RT and the resulting reaction mixture stirred for 1 h. NaBH₄ (3.86 mg, 0.102 mmol) was then added in one portion and stirring continued at RT for 1 h. HPLC purification afforded the title compound as a white solid. MS (ESI, pos. ion) m/z: 456.2 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized:

3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-phenylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(3-(trifluoromethyl)benzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chlorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-chlorobenzyl)-piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(4-(methylsulfonyl)benzyl)piperazin-1-yl)quinoxalin-2-amine, 22,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(4-(trifluoromethyl)-benzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,3-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt

Example 10 Synthesis of 3-(4-(3-chlorobenzyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile

To a solution of 2-(cyclopropylamino)-3-(piperazin-1-yl)quinoxaline-6-carbonitrile, 2HCl (15 mg, 0.041 mmol) and triethylamine (11.38 μl, 0.082 mmol) in DCE (204 μl) was added 3-chlorobenzaldehyde (4.63 μl, 0.041 mmol) then sodium triacetoxyborohydride (12.12 mg, 0.057 mmol). The reaction mixture was stirred at RT for 2 h. ISCO purification (0-100% EtOAc/Hexanes) afforded the title compound as a colorless oil. MS (ESI, pos. ion) m/z: 419.3 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized and purified by either HPLC or ISCO):

N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-6-fluoroquinoxalin-2-amine; 2-(cyclopropylamino)-3-(4-(4-fluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile; 8-chloro-3-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 8-chloro-N-cyclopropyl-3-(4-(2,5-difluorobenzyl)-piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 8-chloro-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 8-chloro-N-cyclopropyl-3-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 2-(4-(2,5-difluorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; 7-bromo-N-cyclopropyl-2-(piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine 2,2,2-trifluoroacetate; 3-(4-(5-chloro-2-propoxybenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(5-(tert-butyl)-2-methoxybenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,6-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chloro-4-fluorobenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chloro-3-fluorobenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(3,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, and 2,2,2-trifluoroacetic acid salt; 3-(4-(2-chloro-5-fluorobenzyl)piperazin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(1-(2,5-dichlorobenzyl)piperidin-4-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(1-(2,5-difluorobenzyl)piperidin-4-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(1-(2,4-difluorobenzyl)piperidin-4-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)-2-methylpiperazin-1-yl)quinoxalin-2-amine; methyl 4-(3-(cyclopropylamino)quinoxalin-2-yl)-1-(2,5-dichlorobenzyl)piperazine-2-carboxylate; N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)-3-isopropylpiperazin-1-yl)quinoxalin-2-amine; N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)-3-methylpiperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)-3-(methoxymethyl)piperazin-1-yl)quinoxalin-2-amine; 3-(3-benzyl-4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt.

Example 11 Synthesis of 2,2,2-trifluoroacetic acid, N-cyclopropyl-3-(4-(3,4-dimethylbenzyl)piperazin-1-yl)quinoxalin-2-amine salt

A mixture of N-cyclopropyl-3-(piperazin-1-yl)quinoxalin-2-amine hydrochloride (100 mg, 0.327 mmol), 4-(chloromethyl)-1,2-dimethylbenzene (152 mg, 0.981 mmol) and Et₃N (0.137 ml, 0.981 mmol) was stirred in DMF (3 ml) at 50° C. for 16 h. HPLC purification yielded the title compound as a yellow oil. MS (ESI, pos. ion) m/z: 388.1 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized:

4-((4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methyl)benzonitrile, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(4-ethylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(3,4-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(naphthalen-2-ylmethyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-bromobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-((4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)methyl)benzonitrile, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(4-fluorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(4-isopropylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(3,5-difluorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,3-dimethylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4-dimethylbenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-chloro-5-fluorobenzyl)-piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-6,7-difluoroquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(2,5-difluorobenzyl)-piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-difluorobenzyl)piperazin-1-yl)-2-(isopropylamino)-quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclobutylamino)-3-(4-(2,5-difluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt.

Example 12 Synthesis of N-cyclopropyl-3-(4-(3-methylbenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazin-2-amine

Step 1: 2-chloro-3-(4-(3-methylbenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazine

To a solution of 2,3-dichloropyrido[2,3-b]pyrazine (100 mg, 0.50 mmol) in dioxane (0.5 mL) was added dropwise a solution of 1-(3-methylbenzyl)piperazine (100 mg, 0.525 mmol) in dioxane (1.0 mL), followed by N-ethyl-N-isopropylpropan-2-amine (0.096 mL, 0.550 mmol). The resulting solution was stirred at RT overnight. Column chromatography purification yielded the title compound as a brown oil.

Step 2: N-cyclopropyl-3-(4-(3-methylbenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazin-2-amine

A solution of 2-chloro-3-(4-(3-methylbenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazine (34.5 mg, 0.097 mmol), cyclopropanamine (7.79 mg, 0.136 mmol) and DIPEA (0.026 mL, 0.146 mmol) in dioxane (0.3 mL) was heated at 100° C. for 8 h. Column chromatography purification gave the title compound as a colorless oil. MS (ESI, pos. ion) m/z: 375.3 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized and purified by either HPLC or ISCO:

3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(4-fluorophenyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; (4-(3-(cyclopentylamino)quinoxalin-2-yl)piperazin-1-yl)(2,5-dichlorophenyl)methanone, 2,2,2-trifluoroacetic acid salt; (2,5-dichlorophenyl)(4-(3-(phenylamino)quinoxalin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; N-(cyclopropylmethyl)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(3-methoxyphenyl)-quinoxalin-2-amine; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(4-methoxyphenyl)-quinoxalin-2-amine; 4-((3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-yl)amino)benzonitrile; N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazin-2-amine; 3-(cyclopropylamino)-2-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-2-(4-(2,5-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-2-(4-(2,5-dichlorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; 2-(4-(4-chlorobenzoyl)piperazin-1-yl)-3-(cyclopropylamino)-quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; (4-chlorophenyl)(4-(3-(cyclopropylamino)pyrido[3,4-b]pyrazin-2-yl)piperazin-1-yl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(cyclopropylamino)-2-(4-(2,5-difluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(cyclopropylamino)-2-(4-((4-fluorophenyl)-sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(cyclopropylamino)-2-(4-((4-fluorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-2-(4-(2,4,5-trifluorobenzyl)-piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-2-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; 2-(4-(2,4-difluorobenzyl)piperazin-1-yl)-N-(2,2-difluoroethyl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; N-(2,2-difluoroethyl)-2-(4-(2,4,5-trifluorobenzyl)-piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-2-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; 2-(4-(2,4-difluorobenzyl)piperidin-1-yl)-N-(2,2-difluoroethyl)pyrido[3,4-b]pyrazin-3-amine; N-cyclopropyl-2-(4-(2,4-difluorobenzyl)piperidin-1-yl)-7-methylpyrido[3,4-b]-pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; 3-(cyclopropylamino)-2-(4-(2,4-difluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(4-(5-chloro-2-fluorobenzyl)piperazin-1-yl)-3-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(cyclopropylamino)-2-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; and 2-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-3-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt.

Example 13 Synthesis of N-(4-bromophenyl)-3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt

A solution of DIPEA (0.026 ml, 0.151 mmol), 1-(3-chlorobenzyl)piperazine (19.06 mg, 0.090 mmol) and 2,3-dichloroquinoxaline (20 mg, 0.100 mmol) in dioxane (0.2 mL) was heated at 60° C. for 6 h. Then DIPEA (0.026 ml, 0.151 mmol) and 4-bromoaniline (25.9 mg, 0.151 mmol) were added. The resulting solution was stirred at 180° C. overnight. HPLC purification gave the title compound as a yellow solid. MS (ESI, pos. ion) m/z: 509.2 (M+1)

Utilizing similar reaction conditions described above, 2-(4-(3-chlorobenzyl)piperazin-1-yl)-N-phenylpyrido[2,3-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt was synthesized.

Example 14 Synthesis of 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-phenylpyrido[2,3-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt

To a solution of 2,3-dichloropyrido[2,3-b]pyrazine (20 mg, 0.100 mmol) in dioxane (0.3 mL) was added aniline (9.78 mg, 0.105 mmol) and N-ethyl-N-isopropylpropan-2-amine (38.8 mg, 0.30 mmol). The reaction mixture was heated at 150° C. overnight, then 1-(3-chlorobenzyl)piperazine (31.6 mg, 0.150 mmol) was added. The resulting solution was heated at 150° C. overnight. HPLC purification afforded the title compound as a yellow solid. MS (ESI, pos. ion) m/z: 431.2 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized:

3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-phenylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(4-(trifluoromethoxy)-phenyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(4-propylphenyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(p-tolyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(4-methoxyphenyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(2-methoxyphenyl)-quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(3-methoxyphenyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-(4-(tert-butyl)phenyl)-3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; and 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(4-isopropoxyphenyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt.

Example 15 Synthesis of 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)pyrido[2,3-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt

Step 1: 2-chloro-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazine

To a solution of 2,3-dichloropyrido[2,3-b]pyrazine (21 mg, 0.105 mmol) and 1-(2,5-dichlorobenzyl)piperazine, HCl (31.0 mg, 0.110 mmol) in dioxane (350 μl) was added N-ethyl-N-isopropylpropan-2-amine (56.8 μl, 0.325 mmol) dropwise at RT. The resulting mixture was stirred at RT overnight and HPLC purification yielded the title compound as a yellow solid.

Step 2: 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)pyrido[2,3-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt

A mixture of 2-chloro-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)pyrido[2,3-b]pyrazine (25 mg, 0.061 mmol), pyridin-3-amine (7.48 mg, 0.080 mmol) and NaH (9.79 mg, 0.245 mmol, 60% in mineral oil) in THF (266 μL) was stirred at RT for 3 h. After quenching with methanol (0.5 mL), HPLC purification afforded the title compound as a yellow solid. MS (ESI, pos. ion) m/z: 466.2 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized:

2-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-3-(pyridin-3-ylamino)quinoxaline-6-carbonitrile; mixture of 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-6-fluoro-N-(pyridin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt and 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-7-fluoro-N-(pyridin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-(pyridin-3-yl)-2-(4-(2,4,5-trifluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; and 2-(4-(2,4-difluorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)pyrido[3,4-b]pyrazin-3-amine

Example 16 Synthesis of 2-(cyclopropylamino)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline-5-carbonitrile, 2,2,2-trifluoroacetic acid salt

A vial containing 5-bromo-N-cyclopropyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine (20 mg, 0.039 mmol), dicyanozinc (2.78 mg, 0.024 mmol), Pd₂(dba)₃ (1.805 mg, 1.971 μmol) and dppf (2.186 mg, 3.94 μmol) in anhydrous NMP (0.3 mL) was evacuated and purged with N₂ (3×). The resulting mixture was heated at 120° C. for 2 h. HPLC purification gave the title compound as a grey solid. MS (ESI, pos. ion) m/z: 453.3 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized:

3-(cyclopropylamino)-2-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline-5-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile; and 3-(cyclopropylamino)-2-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile, 2,2,2-trifluoroacetic acid salt.

Example 17 Synthesis of N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt

Step 1: pyrazino[2,3-d]pyridazine-2,3(1H,4H)-dione

A solution of pyridazine-4,5-diamine (200 mg, 1.816 mmol), oxalic acid (196 mg, 2.179 mmol) and aq hydrogen chloride (2.7 mL, 10.90 mmol, 4.0N) was heated at reflux for 20 h. The reaction mixture was cooled to RT and the resulting precipitate was filtered, washed with water and dried under vacuum to afford the title compound as a white solid.

Step 2: 2,3-dichloropyrazino[2,3-d]pyridazine

A solution of pyrazino[2,3-d]pyridazine-2,3(1H,4H)-dione hydrochloride (300 mg, 1.496 mmol) in phosphoryl trichloride (1812 μl, 19.44 mmol) was heated at 120° C. overnight. Removal of the excess POCl₃ under reduced pressure gave the title compound as a black sticky oil, which was used directly in the next step without further purification.

Step 3: N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt

To a solution of 2,3-dichloropyrazino[2,3-d]pyridazine hydrochloride (48 mg, 0.202 mmol) in DCM (1.0 mL) at 0° C. was added N-ethyl-N-isopropylpropan-2-amine (177 μl, 1.011 mmol) dropwise, followed by slow addition of cyclopropanamine (11.19 μl, 0.162 mmol). The reaction mixture was stirred at 0° C. for 20 min and then 1-(2,4-difluorobenzyl)piperazine hydrochloride (75 mg, 0.303 mmol) and DIPEA (0.2 mL) were added and stirring continued at 0° C. for 30 min. HPLC purification afforded the title compound as a light yellow solid. MS (ESI, pos. ion) m/z: 398.3 (M+1)

Utilizing similar reaction conditions described above, N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt was synthesized.

Example 18 Synthesis of N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt

Step 1: tert-butyl 4-(2,5-difluorobenzylidene)piperidine-1-carboxylate

To a solution of tert-butyl 4-oxopiperidine-1-carboxylate (64.1 mg, 0.322 mmol) in THF (1.6 mL) at −78° C. was added LiHMDS (386 μl, 0.386 mmol, 1.0N in MeOt-Bu). After the reaction mixture was stirred at −78° C. for 30 min, a solution of tert-butyl 4-oxopiperidine-1-carboxylate (64.1 mg, 0.322 mmol) in THF (0.3 mL) was added. The reaction mixture was allowed to warm to RT and and stirred for 48 h. Column chromatography purification gave the title compound as a white solid.

Step 2: 4-(2,5-difluorobenzylidene)piperidine

To a solution of tert-butyl 4-(2,5-difluorobenzylidene)piperidine-1-carboxylate (20 mg, 0.065 mmol) in DCM (0.6 ml) at 0° C. was added TFA (0.3 mL, 3.89 mmol) and stirring continued at 0° C. for 2 h. Removal of the solvent yielded the title compound as a colorless oil, which was used directly in the next step without further purification.

Step 3: N-cyclopropyl-3-(4-(2,5-difluorobenzylidene)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine

A solution of 3-chloro-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine (127 mg, 0.574 mmol), 4-(2,5-difluorobenzylidene)piperidine (100 mg, 0.478 mmol) and DIPEA (167 μl, 0.956 mmol) in dioxane (0.8 mL) was heated at 80° C. for 8 h. HPLC purification afforded the title compound.

Step 4: N-cyclopropyl-3-(4-(2,5-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt

To a solution of N-cyclopropyl-3-(4-(2,5-difluorobenzylidene)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine 2,2,2-trifluoroacetate (21.2 mg, 0.042 mmol) in MeOH (209 μl) was added 10% Pd/C (4 mg, 3.76 μmol). The reaction mixture was stirred under a H₂ atmosphere overnight. HPLC purification yielded the title compound as a light yellow solid. MS (ESI, pos. ion) m/z: 396.3 (M+1)

Example 19 Synthesis of N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)-7-methoxypyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt

A vial charged with 7-chloro-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine (15 mg, 0.035 mmol), Pd₂(dba)₃ (2.56 mg, 2.79 μmol), and Cs₂CO₃ (11.37 mg, 0.035 mmol) was evacuated and purged with N₂ (3×). After MeOH (0.3 ml) was added, the mixture was again evacuated and purged with N₂ (2×) and then heated at 100° C. overnight. HPLC purification gave the title compound as a grey solid. MS (ESI, pos. ion) m/z: 426.3 (M+1)

Example 20 Synthesis of 2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-7-ol, 2,2,2-trifluoroacetic acid salt

A vial charged with 7-chloro-N-cyclopropyl-3-(4-(2,4-difluorobenzyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine (25 mg, 0.058 mmol), Pd₂(dba)₃ (4.26 mg, 4.65 μmol), potassium trimethylsilanolate (22.38 mg, 0.174 mmol) and cesium carbonate (18.95 mg, 0.058 mmol) was evacuated and purged with N₂ (3×). After DMF (0.29 mL) was added, the mixture was again evacuated and purged with N₂ (2×) and then heated at 110° C. overnight. HPLC purification yielded the title compound as a yellow solid. MS (ESI, pos. ion) m/z: 412.3 (M+1)

Example 21 Synthesis of 2-(cyclopropylamino)-3-(4-(phenylsulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile

To a solution of 2-(cyclopropylamino)-3-(piperazin-1-yl)quinoxaline-6-carbonitrile, 2HCl (15 mg, 0.041 mmol) in CH₂Cl₂ (204 μl) was added triethylamine (17.08 μl, 0.123 mmol). After stirring for 10 min, benzenesulfonyl chloride (6.27 μl, 0.049 mmol) was added and the reaction mixture was stirred at RT for 2 h. ISCO purification (0-60% EtOAc/Hexanes) afforded the title compound as a white solid. MS (ESI, pos. ion) m/z: 435.3 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized and purified by either ISCO or HPLC:

3-(4-(phenylsulfonyl)piperazin-1-yl)-N-(pyridin-3-yl)quinoxalin-2-amine; N-cyclopropyl-6-fluoro-3-(4-(phenylsulfonyl)piperazin-1-yl)quinoxalin-2-amine; 3-(4-((3-chlorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile; 3-(4-((3-chlorophenyl)sulfonyl)piperazin-1-yl)-N-cyclopropyl-6-fluoroquinoxalin-2-amine; 2-(cyclopropylamino)-3-(4-((2,5-dichlorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile; 2-(cyclopropylamino)-3-(4-(o-tolylsulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile; 2-(cyclopropylamino)-3-(4-(m-tolylsulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile; 2-(cyclopropylamino)-3-(4-tosylpiperazin-1-yl)quinoxaline-6-carbonitrile; 3-(4-((2-bromophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile; 3-(4-((3-bromophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile; 3-(4-((4-bromophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)-quinoxaline-6-carbonitrile; N-cyclopropyl-3-(4-((4-fluorophenyl)sulfonyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-2-(4-((4-fluorophenyl)sulfonyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-3-amine, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((3,5-dimethylisoxazol-4-yl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((2,5-dimethylphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((4-methoxyphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((2-methoxyphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((3-methoxyphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((5-chlorothiophen-2-yl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(mesitylsulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((2-methoxy-4-methylphenyl)sulfonyl)-piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((5-chloro-1,3-dimethyl-1H-pyrazol-4-yl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((2,3,4-trifluorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((4-(tert-butyl)phenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((4-chloro-2,5-dimethylphenyl)-sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((3-chloro-5-fluoro-2-methylphenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((4-(trifluoromethoxy)phenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((5-bromothiophen-2-yl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((4-bromo-2-fluorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((2-chloro-5-(trifluoromethyl)phenyl)-sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((4-bromo-2-chlorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((4-ethylphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((2-fluoro-5-methylphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((3,4-difluorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((2,5-dimethoxyphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((2-chloro-4-(trifluoromethyl)phenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((3-cyano-4-fluorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((5-chloro-2-methoxyphenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((5-chloro-2,4-difluorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((5-bromo-6-chloropyridin-3-yl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((4-bromo-2,5-difluorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((2,4-dimethoxyphenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile; N-cyclopropyl-3-(4-(phenylsulfonyl)piperazin-1-yl)quinoxalin-2-amine; N-cyclopropyl-3-(4-((4-(trifluoromethoxy)phenyl)sulfonyl)piperazin-1-yl)quinoxalin-2-amine; 3-(4-(cyclopentylsulfonyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine; 3-(4-((4-chlorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((3-fluorophenyl)sulfonyl)-piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((2-fluorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((2-chlorophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-((4-fluorophenyl)sulfonyl)piperazin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((2-cyanophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((3-cyanophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-((4-cyanophenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; and N-cyclopropyl-3-(4-((4-(trifluoromethyl)phenyl)sulfonyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt.

Example 22 Synthesis of N-cyclopropyl-3-(4-phenethylpiperazin-1-yl)quinoxalin-2-amine

Step 1: 1-(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)-2-phenylethanone

To a solution of 2-phenylacetic acid (11.93 mg, 0.088 mmol) in CH₂Cl₂ (438 μl) was added DMF (3 drops) and oxalyl chloride (11.51 μl, 0.131 mmol), then the mixture was allowed to stir for 60 min. The acid chloride was added to a solution of N-cyclopropyl-3-(piperazin-1-yl)quinoxalin-2-amine, 2HCl (30 mg, 0.088 mmol) and triethylamine (36.7 μl, 0.263 mmol) in CH₂Cl₂ (400 μl). The reaction mixture was allowed to stir at RT for 2 h. ISCO purification (0-100% EtOAc/Hexanes yielded the title compound as a yellow oil.

Step 2: N-cyclopropyl-3-(4-phenethylpiperazin-1-yl)quinoxalin-2-amine

To a solution of 1-(4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)-2-phenylethanone (5 mg, 0.013 mmol) in THF (43.0 μl) was added BH₃-THF (64.5 μl, 0.065 mmol, 1 M in THF). The mixture was stirred at RT for 16 h. ISCO purification (0-80% EtOAc/Hexanes) afforded the title compound as a yellow oil. MS (ESI, pos. ion) m/z: 374.3 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized and purified by either HPLC or ISCO:

3-(4-(4-chlorophenethyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine; N-cyclopropyl-3-(4-(4-methoxyphenethyl)piperazin-1-yl)quinoxalin-2-amine; N-cyclopropyl-3-(4-(2,5-dichlorophenethyl)piperazin-1-yl)quinoxalin-2-amine

Example 23 Synthesis of 3-(4-benzylpiperidin-1-yl)-N-phenylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt

Step 1: 2-(4-benzylpiperidin-1-yl)-3-chloroquinoxaline

A solution of 2,3-dichloroquinoxaline (1 g, 5.02 mmol) and EtOH (25 ml) was treated with 4-benzylpiperidine (1.233 g, 7.03 mmol). The reaction mixture was stirred at 15° C. for 15 h. The solvent was removed under reduced pressure to give the title compound, which was used for the next step without further purification.

Step 2: 3-(4-benzylpiperidin-1-yl)-N-phenylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt

2-(4-Benzylpiperidin-1-yl)-3-chloroquinoxaline (200 mg, 0.592 mmol) and aniline (55.1 mg, 0.592 mmol) was stirred in n-BuOH (0.6 ml) at 90° C. for 16 h. The solvent was removed under reduced pressure and HPLC purification afforded the title compound as a yellow solid.

Utilizing similar reaction conditions described above, following compounds were synthesized:

N-(3-bromophenyl)-3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-(2-bromophenyl)-3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(pyridin-3-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(pyridin-4-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-(3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-yl)-1,3,4-thiadiazol-2-amine, 2,2,2-trifluoroacetic acid salt; N-(3-(4-(3-chlorobenzyl)piperazin-1-yl)quinoxalin-2-yl)thiazol-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(pyrimidin-2-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; and 3-(4-(3-chlorobenzyl)piperazin-1-yl)-N-(pyrimidin-5-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt.

Example 24 Synthesis of 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-isobutylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt

Step 1: 2-chloro-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline

A suspension of 2-chloro-3-(piperazin-1-yl)quinoxaline (2.5 g, 10.05 mmol), 1,4-dichloro-2-(chloromethyl)benzene (2.358 g, 12.06 mmol) and Et₃N (4.20 ml, 30.2 mmol) in DMF (20 ml) was stirred at RT for 16 h. The reaction mixture was poured into water and extracted with EtOAc. The organic phase was dried, concentrated, and chromatographed on silica gel to give the title compound.

Step 2: 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-isobutylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt

A suspension of 2-chloro-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxaline (50 mg, 0.123 mmol) and 2-methylpropan-1-amine (90 mg, 1.226 mmol) was heated in n-BuOH (1 ml) at 130° C. under microwave irradiation for 1 h. HPLC purification afforded the title compound as a white solid. MS (ESI, pos. ion) m/z: 444.0 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized using commercially available amines:

3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-isopropylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2-ethylbutyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(4-methylpentan-2-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-neopentylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-isopentylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-(sec-butyl)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-propylquinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2-methoxyethyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclobutyl-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-(tert-butyl)-3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(3,3-dimethylbutyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2-ethoxyethyl)-quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(2-isopropoxyethyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(3-ethoxypropyl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclohexyl-3-(4-((2,5-dichlorobenzyl)piperazin-1-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-dichlorobenzyl)piperazin-1-yl)-N-(tetrahydro-2H-pyran-4-yl)quinoxalin-2-amine, 2,2,2-trifluoroacetic acid salt; and (R)-2-((3-(4-(2,5-dichlorobenzyl)-piperazin-1-yl)quinoxalin-2-yl)amino)propan-1-ol, 2,2,2-trifluoroacetic acid salt

Example 25 Synthesis of (R/S)—N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine

Step 1: (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,4-difluorophenyl)methanol

To a solution of (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,4-difluorophenyl)methanone, TFA (50 mg, 0.096 mmol) in MeOH (478 μl) was added NaBH₄ (10.84 mg, 0.287 mmol). The mixture was stirred at RT for 2 h then purified by ISCO (0-100% EtOAc/hexanes) to yield the title compound as a colorless oil.

Step 2: (R/S)—N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine

To a −78° C. solution of (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(2,4-difluorophenyl)methanol (7 mg, 0.017 mmol) in CH₂Cl₂ (85 μl) was added DAST (6.74 μl, 0.051 mmol). The reaction mixture was stirred for 30 min then quenched with a few drops of MeOH. ISCO purification (0-100% EtOAc/hexanes) yielded the title compound as a colorless oil. MS (ESI, pos. ion) m/z: 414.3 (M+1)

Note: Optically pure final compounds were obtained by chiral SFC separation of racemic compound.

Utilizing similar reaction conditions described above, following compounds were synthesized:

(R/S)—N-cyclopropyl-3-(4-(fluoro (4-fluorophenyl)methyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine; (R/S)-3-(4-((5-chloro-2-fluorophenyl)fluoromethyl)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine; (R/S)—N-cyclopropyl-3-(4-((2,5-difluorophenyl)-fluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine; and (R/S)—N-cyclopropyl-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine

Example 26 Synthesis of (S)—N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine 2,2,2-trifluoroacetate

To a solution of 3-chloro-N-cyclopropyl-7-methylpyrido[3,4-b]pyrazin-2-amine (10 mg, 0.043 mmol) in dioxane (85 μl) was added (S)-4-((2,4-difluorophenyl)fluoromethyl)piperidine, HCl (14.72 mg, 0.055 mmol) and iPr₂EtN (29.8 μl, 0.170 mmol). The mixture was heated at 80° C. for 2 h. HPLC purification afforded the title compound as a yellow oil. MS (ESI, pos. ion) m/z: 428.3 (M+1)

Utilizing similar reaction conditions described above, following compounds were synthesized

using chiral intermediate compounds: (R)—N-cyclopropyl-3-(4-((2,4-difluorophenyl)-fluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (S)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)-piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; (S)—N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-5-methylpyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (S)—N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; (R)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt; (R)-7-chloro-N-cyclopropyl-3-(4-((2,4-difluorophenyl)-fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt; and (S)-7-chloro-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt.

Example 27 Synthesis of (R/S)-3-(4-(1-(5-chloro-2-fluorophenyl)-1-fluoroethyl)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine

Step 1: 1-(5-chloro-2-fluorophenyl)-1-(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)ethanol

To a −78° C. solution of (5-chloro-2-fluorophenyl)(1-(2-(cyclopropylamino)-pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone, TFA (18 mg, 0.033 mmol) in THF (167 μl) was added methyl magnesium bromide (33.3 μl, 0.100 mmol, 3 M in Et₂O). The mixture was stirred at −78° C. for 1 h then RT for 1 h. A few drops of H₂O were added to quench the reaction, which was then filtered through a syringe filter and the solvents were removed under reduced pressure to yield the title compound as a tan solid.

Step 2: (R/S)-3-(4-(1-(5-chloro-2-fluorophenyl)-1-fluoroethyl)piperidin-1-yl)-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine

To a −78° C. solution of 1-(5-chloro-2-fluorophenyl)-1-(1-(2-(cyclopropylamino)-pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)ethanol (13 mg, 0.029 mmol) in CH₂Cl₂ (147 μl) was added DAST (11.66 μl, 0.088 mmol). The mixture was stirred at −78° C. for 30 min then warmed to 10° C. and added another 3 eq DAST (11.66 μl, 0.088 mmol). The reaction mixture was quenched with a few drops of H₂O and ISCO purification (30-100% EtOAc/hexanes) afforded the title compound as a colorless oil. MS (ESI, pos. ion) m/z: 444.2 (M+1)

Example 28 Synthesis of (R/S)-3-(4-((2,5-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile, 2,2,2-trifluoroacetic acid salt

A solution of (R/S)-4-((2,5-difluorophenyl)fluoromethyl)piperidine hydrochloride (28 mg, 0.105 mmol) and 3-chloro-2-(isopropylamino)quinoxaline-6-carbonitrile (20 mg, 0.081 mmol) in dioxane (162 μl) and DIPEA (42.5 μl, 0.243 mmol) was stirred at 75° C. for 3 h. HPLC purification afforded the title compound as an ivory solid. MS (ESI, pos. ion) m/z: 440.3 (M+1)

Note: Optically pure final compounds were obtained by chiral SFC separation of racemic compound.

Utilizing similar reaction conditions described above, following compounds were synthesized:

(R/S)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile; (R/S)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-2-(isopropylamino)quinoxaline-6-carbonitrile; and (R/S)-3-(cyclopropylamino)-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile.

Example 29 Synthesis of (S)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile

Step 1: 7-bromo-3-chloro-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine

To solution of 7-bromo-2,3-dichloropyrido[3,4-b]pyrazine (90 mg, 0.323 mmol) in DCM (1613 μl) at 0° C. was added a solution of cyclopropanamine (26.8 μl, 0.387 mmol) in DCM (0.2 mL), followed by the addition of DIPEA (169 μl, 0.968 mmol). The resulting solution was stirred at 0° C. for 2 h. ISCO purification (0-50% EtOAc/Hexanes) gave the title compound as an off-white solid.

Step 2: (S)-7-bromo-N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine

A mixture of 7-bromo-3-chloro-N-cyclopropylpyrido[3,4-b]pyrazin-2-amine (30 mg, 0.100 mmol), (S)-4-((2,4-difluorophenyl)fluoromethyl)piperidine, HCl (31.9 mg, 0.120 mmol) and DIPEA (0.052 ml, 0.300 mmol) in dioxane (0.3 ml) was heated at 80° C. for 8 h. Silica gel column chromatography purification gave the title compound as a white solid.

Step 3: (S)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile

To a vial was added (S)-7-bromo-N-cyclopropyl-3-(4-((2,4-difluorophenyl)-fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine (25 mg, 0.051 mmol), Pd₂(dba)₃ (2.325 mg, 2.54 μmol), dicyanozinc (3.58 mg, 0.030 mmol) and dppf (2.82 mg, 5.08 μmol) in NMP (508 μl). The vial was evacuated and filled with N₂ (3×) then heated at 120° C. for 2 h. HPLC and ISCO purification afforded the title compound as a white solid. MS (ESI, pos. ion) m/z: 439.2 (M+1)

Utilizing similar reaction conditions described above, using reference compounds, the following compounds were synthesized: (R)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile; 3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-2-(isopropylamino)pyrido[3,4-b]pyrazine-7-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-difluorobenzoyl)piperidin-1-yl)-2-(isopropylamino)pyrido[3,4-b]pyrazine-7-carbonitrile, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-fluoro-4-methoxybenzyl)piperidin-1-yl)-2-(isopropylamino)pyrido[3,4-b]pyrazine-7-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-((2,2-difluoroethyl)amino)-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(tert-butylamino)-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile

Example 30 Synthesis of (S)-3-(cyclopropylamino)-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile

Step 1: (S)-7-bromo-3-chloro-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazine

To a mixture of 7-bromo-2,3-dichloropyrido[3,4-b]pyrazine (30 mg, 0.108 mmol) in DCM (1 ml) at 0° C. was added (S)-4-((2,4-difluorophenyl)fluoromethyl)piperidine, HCl (31.4 mg, 0.118 mmol), followed by addition of N-ethyl-N-isopropylpropan-2-amine (0.056 ml, 0.323 mmol). The resulting mixture was stirred at 0° C. for 2 h. ISCO purification gave the title compound as a yellow solid.

Step 2: (S)-7-bromo-N-cyclopropyl-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-3-amine

A solution of (S)-7-bromo-3-chloro-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazine (40 g, 85 mmol), cyclopropanamine (38.7 g, 678 mmol) and DIPEA (22.22 ml, 127 mmol) in dioxane (0.3 ml) was heated at 80° C. for 24 h. Silica gel column chromatography purification gave the title compound as a white solid.

Step 3: (S)-3-(cyclopropylamino)-2-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile

To a vial was added (S)-7-bromo-N-cyclopropyl-2-(4-((2,4-difluorophenyl)-fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-3-amine (17 mg, 0.035 mmol), Pd₂(dba)₃ (1.581 mg, 1.726 μmol), dicyanozinc (2.433 mg, 0.021 mmol) and dppf (1.914 mg, 3.45 μmol) in NMP (345 μl). The vial was evacuated and filled with N₂ (3×) then heated at 120° C. for 2 h. HPLC and ISCO purification afforded the title compound as a white solid. MS (ESI, pos. ion) m/z: 439.2 (M+1).

Utilizing similar reaction conditions described above, (R)-3-(cyclopropylamino)-2-(4-((2,4-difluorophenyl)-fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazine-7-carbonitrile was synthesized.

Example 31 Synthesis of 2,2,2-trifluoroacetic acid, 1-(4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)phenyl)ethanol salt

A 5 mL screwtop vial containing 1-(4-((1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)oxy)phenyl)ethanone 2,2,2-trifluoroacetate (130 mg, 0.251 mmol) and sodium tetrahydroborate (28.5 mg, 0.754 mmol) in MeOH (1256 μl) was stirred for 30 min. HPLC purification afforded the title compound as a clear oil. MS (ESI, pos. ion) m/z: 406.3 (M+1).

Example 32 Synthesis of 2-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-3-(isopropylamino)quinoxaline-6-carbonitrile

Step 1: 3-chloro-2-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)quinoxaline-6-carbonitrile

To a solution of 2,3-dichloroquinoxaline-6-carbonitrile (400 mg, 1.785 mmol) and 4-(4-chloro-2-fluorophenoxy)piperidine (615 mg, 2.68 mmol) in dichloromethane (40 ml) was added triethylamine (0.025 ml, 0.179 mmol), which was stirred at 20° C. for 6 h. Water was added and the reaction was extracted with dichloromethane (2×) and the combined organic layers were concentrated. Purification by column chromatography (PE:EtOAc=50:1) afforded the title compound as a yellow solid.

Step 2: 2-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-3-(isopropylamino)quinoxaline-6-carbonitrile

To a solution of 3-chloro-2-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)quinoxaline-6-carbonitrile (100 mg, 0.240 mmol) in DMSO (10 ml) was added triethylamine (0.033 ml, 0.240 mmol) and propan-2-amine (142 mg, 2.397 mmol), which was stirred at 120° C. for 16 h. HPLC purification afforded the title compound as a yellow solid. MS (ESI, pos. ion) m/z: 439.8 (M+1).

Utilizing similar reaction conditions described above, 2-(4-(2-chloro-5-(isopropylamino)benzoyl)piperidin-1-yl)-3-(isopropylamino)quinoxaline-6-carbonitrile was synthesized.

Example 33 Synthesis of 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-2-(isopropylamino)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt

Step 1: 7-bromo-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-2-amine

A solution of 4-(2,4-difluorophenoxyl)piperidine hydrochloride (150 mg, 0.599 mmol) and 7-bromo-3-chloro-N-isopropylpyrido[3,4-b]pyrazin-2-amine (139 mg, 0.461 mmol) in dioxane (922 μl) and DIPEA (242 μl, 1.383 mmol) was stirred at 90° C. for 4 h. ISCO purification (40% EtOAc in hexanes) afforded the title compound as an orange solid.

Step 2: 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-2-(isopropylamino)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt

A solution of 7-bromo-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-2-amine (30 mg, 0.063 mmol), phenyl formate (13.68 μl, 0.125 mmol), diacetoxypalladium (2.82 mg, 0.013 mmol), (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine) (14.52 mg, 0.025 mmol) and triethylamine (17.48 μl, 0.125 mmol) in MeCN (314 μl) was stirred at 80° C. overnight. Dimethylamine (157 μl, 0.314 mmol) was then added and stirring continued at 80° C. for 1 h. HPLC purification afforded the title compound as a yellow solid. MS (ESI, pos. ion) m/z: 471.3 (M+1).

Utilizing similar reaction conditions described above, the following compounds were synthesized: 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-2-(isopropylamino)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-2-(isopropylamino)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,5-difluorobenzoyl)piperidin-1-yl)-2-(isopropylamino)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt; (S)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt; (R)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt; (S)-(2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-7-yl)(morpholino)methanone, 2,2,2-trifluoroacetic acid salt; (R)-(2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-7-yl)(morpholino)methanone, 2,2,2-trifluoroacetic acid salt; (2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-7-yl)(4-methylpiperazin-1-yl)methanone; 2,2,2-trifluoroacetic acid salt; (2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazin-7-yl)(morpholino)methanone, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxybenzyl)piperazin-1-yl)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt; 2-((2,2-difluoroethyl)amino)-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide;

Example 34 Synthesis of 3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt

Step 1: pyrazino[2,3-d]pyridazine-2,3(1H,4H)-dione

A mixture of pyridazine-4,5-diamine (4 g, 36.3 mmol) and di(1H-imidazol-1-yl)methanone (7.07 g, 43.6 mmol) in DMF (145 ml) was heated at 75° C. for 16 h. Then 60 mL THF was added and the reaction mixture was stirred at RT for 1 h. Filtration, followed by wash with THF, gave the title compound as a grey powder. The material was used directly in the next step without further purification.

Step 2: 2,3-dichloropyrazino[2,3-d]pyridazine

A mixture of pyrazino[2,3-d]pyridazine-2,3(1H,4H)-dione (1 g, 6.09 mmol) in phosphoryl trichloride (22.72 ml, 244 mmol) was heated at 133° C. for 24 h. After removal of POCl₃ in vacuo, ice was added to the reaction flask. Then, 120 mL cold ethyl acetate was added and the mixture was made basic with sat. NaHCO₃ while at 0° C. After filtration, the organic layer was quickly separated and dried with Na₂SO₄. After the drying agent was filtered off, the filtrate was used immediately in the next step without further purification.

Step 3: 3-chloro-N-isopropylpyrazino[2,3-d]pyridazin-2-amine

Half of the above ethyl acetate solution was transferred to a reaction flask at 0° C., then propan-2-amine (0.052 ml, 0.607 mmol) and DIPEA (0.530 ml, 3.03 mmol) was added. The reaction mixture was stirred at 0° C. for 15 min and then used in the next step without purification.

Step 4: 3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt

Half of the reaction solution was transferred to a reaction flask at 0° C., and then 4-(2-fluoro-4-methoxyphenoxy)piperidine, HCl (0.199 g, 0.760 mmol) and N-ethyl-N-isopropylpropan-2-amine (0.265 ml, 1.520 mmol) were added. The reaction mixture was stirred at 0° C. for 1 h and at RT for 2 h. HPLC purification afforded the title compound as a brown solid. MS (ESI, pos. ion) m/z: 413.4 (M+1).

Utilizing similar reaction conditions described above, the following compounds were synthesized: (S)—N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; (R)—N-cyclopropyl-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2-fluoro-4-(methylthio)phenoxy)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; N-cyclopropyl-3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; 4-((1-(3-(cyclopropylamino)pyrazino[2,3-d]pyridazin-2-yl)piperidin-4-yl)oxy)-3-fluorophenol; 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; (S)—N-(sec-butyl)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; (R)—N-(sec-butyl)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-fluoro-4-((1-(3-(isopropylamino)pyrazino[2,3-d]pyridazin-2-yl)piperidin-4-yl)oxy)benzonitrile, 2,2,2-trifluoroacetic acid salt; (R)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; (2-fluoro-4-methoxyphenyl)(1-(3-(isopropylamino)pyrazino[2,3-d]pyridazin-2-yl)piperidin-4-yl)methanone, 2,2,2-trifluoroacetic acid salt; 3-(4-(2-fluoro-4-methoxybenzyl)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-((R)-(2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)-N-((1R,2R)-2-methylcyclopropyl)pyrazino[2,3-d]pyridazin-2-amine, 2,2,2-trifluoroacetic acid salt; 3-(4-(2,4-difluorobenzyl)piperazin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine 2,2,2-trifluoroacetate; N-isopropyl-3-(4-(3-methoxyphenoxyl)piperidin-1-yl)pyrazino[2,3-d]pyridazin-2-amine 2,2,2-trifluoroacetate; 3-(4-(4-chloro-2-fluorophenoxy)piperidin-1-yl)-N-cyclopropylpyrazino[2,3-d]pyridazin-2-amine 2,2,2-trifluoroacetate; 3-(4-(2-fluoro-4-(fluoromethoxy)phenoxy)piperidin-1-yl)-N-isopropylpyrazino[2,3-d]pyridazin-2-amine.

Example 35 Synthesis of 2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-N,N-dimethylpyrido[3,4-b]pyrazine-5-carboxamide

A vial was charged with 5-chloro-N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine (40 mg, 0.090 mmol), diacetoxypalladium (4.05 mg, 0.018 mmol), (9,9-dimethyl-9H-xanthene-4,5-diyl)bis(diphenylphosphine) (20.86 mg, 0.036 mmol), phenyl formate (22.01 mg, 0.180 mmol) and triethylamine (24.91 μl, 0.180 mmol). The vial was purged with nitrogen and MeCN (410 μl) was added. The mixture was heated at 100° C. for 14 h. Then, dimethylamine (225 μl, 0.451 mmol) in THF was added and the mixture was stirred at RT for 2 h. HPLC purification afforded the title compound as a yellow solid. MS (ESI, pos. ion) m/z: 481.4 (M+1).

Utilizing similar reaction conditions described above, and using commercially available amines, the following compounds were synthesized: (2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-5-yl)(morpholino)methanone, 2,2,2-trifluoroacetic acid salt; azetidin-1-yl(2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-5-yl)methanone, 2,2,2-trifluoroacetic acid salt.

Example 36 Synthesis of 2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazine-5-carbonitrile, 2,2,2-trifluoroacetic acid salt

To a vial was added 5-chloro-N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine (22 mg, 0.050 mmol), dicyanozinc (5.82 mg, 0.050 mmol), zinc (2.59 mg, 0.040 mmol), bis(2,2,2-trifluoroacetyl)palladium (4.47 mg, 0.015 mmol) and [1,1′-binaphthalen]-2-yldi-tert-butylphosphine (11.85 mg, 0.030 mmol). After purging with nitrogen for 2 min, NMP (248 μl) was added. The resulting reaction mixture was heated at 100° C. overnight. HPLC purification yielded the title compound as a light yellow film. MS (ESI, pos. ion) m/z: 435.3 (M+1).

Utilizing similar reaction conditions described above, and using reference compounds, the following compounds were synthesized: 2-(cyclopropylamino)-3-(4-(2,4-difluorobenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazine-5-carbonitrile, 2,2,2-trifluoroacetic acid salt; 2-(cyclopropylamino)-3-(4-(2-fluoro-4-methoxybenzyl)piperazin-1-yl)pyrido[3,4-b]pyrazine-5-carbonitrile, 2,2,2-trifluoroacetic acid salt.

Example 37 Synthesis of N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-5-morpholinopyrido[3,4-b]pyrazin-2-amine, 2,2,2-trifluoroacetic acid salt

A solution of 5-chloro-N-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-2-amine (13 mg, 0.029 mmol), morpholine (3.83 μl, 0.044 mmol) and DIPEA (0.015 ml, 0.088 mmol) in dioxane (0.25 ml) was heated at 150° C. overnight. HPLC purification gave the title compound as white solid. MS (ESI, pos. ion) m/z: 495.4 (M+1).

Utilizing similar reaction conditions described above, and using commercially available amines, the following compounds were synthesized: N2-cyclopropyl-3-(4-(2-fluoro-4-methoxyphenoxy)piperidin-1-yl)-N5,N5-dimethylpyrido[3,4-b]pyrazine-2,5-diamine, 2,2,2-trifluoroacetic acid salt.

Example 38 Synthesis of 2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-3-amine

Step 1: 3-chloro-2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazine

A 500 mL round bottom flask equipped with a stir bar, septum, and N2 inlet was charged with 2,3-dichloropyrido[3,4-b]pyrazine (9.0 g, 36.0 mmol), 4-(2,4-difluorophenoxyl)piperidine hydrochloride (9.44 g, 37.8 mmol), and DCM (90 ml) to furnish an orange suspension. Next, N-ethyl-N-isopropylpropan-2-amine (18.81 ml, 108 mmol) was added to the flask over 2 min at 0° C. The reaction mixture was stirred at 0° C. for 3 h under nitrogen to furnish an orange suspension. The reaction mixture was partitioned between saturated aqueous NH4Cl (100 mL), EtOAc (500 mL), MeOH (50 mL) and H2O (25 mL) to furnish two layers. The layers were separated and the aqueous phase was washed with EtOAc (2×100 mL). MeOH (10 mL) was added during each phase separation. The organic extracts were combined, washed with saturated NaHCO3 (100 mL), brine (100 mL), dried over Na2SO4, filtered, rinsed with EtOAc, and dried in vacuo. Purification by silica gel column (10-50% EtOAc in hexanes) provided the title compound as a yellow-orange solid.

Step 2: 2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-3-fluoropyrido[3,4-b]pyrazine

To a vial charged with 3-chloro-2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazine (1.0 g, 2.65 mmol) and potassium fluoride (0.200 g, 3.45 mmol) was added DMSO (5.0 mL) in one portion at 23° C. The mixture was stirred at 23° C. for 2 h to furnish an orange suspension. The crude reaction mixture was used in the next step without further workup or purification.

Step 3: 2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropylpyrido[3,4-b]pyrazin-3-amine

To the crude reaction mixture of 2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-3-fluoropyrido[3,4-b]pyrazine was added N-ethyl-N-isopropylpropan-2-amine (0.924 mL, 5.31 mmol) and propan-2-amine (0.684 mL, 7.96 mmol) at 23° C. to furnish a red solution. The reaction mixture was stirred at 23° C. for 20 h. The reaction mixture was diluted with H2O (20 mL) and stirred for 15 min at 23° C. to furnish an orange suspension. The resulting solid was filtered, rinsed with H2O and dried in vacuo. Purification on silica gel (0-100% ethyl acetate in heptanes) provided the title compound as a light yellow solid. MS (ESI, pos. ion) m/z: 400.0 (M+1).

Utilizing similar reaction conditions described above, and using commercially available amines, the following compound was synthesized: N-cyclobutyl-2-(4-(2,4-difluorophenoxyl)piperidin-1-yl)pyrido[3,4-b]pyrazin-3-amine.

Example 39 Synthesis of 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropyl-5,8-dimethylpyrazino[2,3-d]pyridazin-2-amine 2,2,2-trifluoroacetate

Step 1: 5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazine-2,3-dicarbaldehyde

A solution of (5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazine-2,3-diyl)dimethanol (100 mg, 0.245 mmol) and Dess-Martin Periodinane (260 mg, 0.612 mmol) in DCM (2448 μl) was stirred at RT for 3 h. The reaction mixture was quenched with 2 mL sat. Na₂S₂O₄ and sat. NaHCO₃ and stirred at RT for 15 min. ISCO purification gave the title compound as a yellow solid.

Step 2: 1,1′-(5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazine-2,3-diyl)diethanol

To a solution of 5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazine-2,3-dicarbaldehyde (32 mg, 0.079 mmol) in degassed THF (1 mL) at −78° C. was added methylmagnesium bromide (0.198 mL, 0.277 mmol, 1.4 M in toluene). The reaction was stirred at −78° C. for 2 h then ethyl acetate (3 mL) was added, followed by sat. NaHCO₃ (3 mL). The mixture was allowed to warm to RT then the aqueous layer was extracted with ethyl acetate (5 mL×2). ISCO purification (0-100% ethyl acetate in heptanes) gave the title compound as a yellow oil.

Step 3: 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropyl-5,8-dimethylpyrazino[2,3-d]pyridazin-2-amine 2,2,2-trifluoroacetate

A solution of 1,1′-(5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazine-2,3-diyl)diethanol (13 mg, 0.030 mmol) and Dess-Martin Periodinane (29.1 mg, 0.069 mmol) in DCM (298 μl) was stirred at RT for 5 h. Then, 3 drops of NH₂NH₂—H₂O were added to the reaction mixture and stirring continued for 1 h. HPLC purification gave the title compound as a brown solid. MS (ESI, pos. ion) m/z: 428.9 (M+1).

Example 40 Synthesis of 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropyl-8-methylpyrazino[2,3-d]pyridazin-2-amine

Step 1: (3-(((tert-butyldimethylsilyl)oxy)methyl)-5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazin-2-yl)methanol and (3-(((tert-butyldimethylsilyl)oxy)methyl)-6-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-5-(isopropylamino)pyrazin-2-yl)methanol

To a solution of (5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazine-2,3-diyl)dimethanol (800 mg, 1.959 mmol) in DCM (9793 μl) at 0° C. was added DIPEA (513 μl, 2.94 mmol), followed a solution of TBS-Cl (310 mg, 2.057 mmol) in DCM (3 mL), and one crystal of DMAP. The reaction was stirred at 0° C. for 3 h and then RT overnight. ISCO purification (0-50% ethyl acetate in heptane) gave a mixture of the title compounds as a colorless oil.

Step 2: 3-(((tert-butyldimethylsilyl)oxy)methyl)-5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazine-2-carbaldehyde and 3-(((tert-butyldimethylsilyl)oxy)methyl)-6-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-5-(isopropylamino)pyrazine-2-carbaldehyde

A solution of (3-(((tert-butyldimethylsilyl)oxy)methyl)-5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazin-2-yl)methanol (598 mg, 1.144 mmol, as a mixture of regioisomers) and Dess-Martin Periodinane (728 mg, 1.716 mmol) in DCM (11.4 mL) was stirred at RT for 3 h. Then, sat. NaHCO₃ (10 mL) and sat. Na₂S₂O₃ (10 mL) were added and the resulting mixture was stirred vigorously for 15 min. The organic phase was extracted with ethyl acetate (10 mL×2). ISCO purification (0-100% ethyl acetate in heptane) gave a mixture of the title compounds as a light yellow oil.

Step 3: 1-(3-(((tert-butyldimethylsilyl)oxy)methyl)-5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazin-2-yl)ethanol and 1-(3-(((tert-butyldimethylsilyl)oxy)methyl)-6-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-5-(isopropylamino)pyrazin-2-yl)ethanol

To a solution of 3-(((tert-butyldimethylsilyl)oxy)methyl)-6-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-5-(isopropylamino)pyrazine-2-carbaldehyde (241 mg, 0.463 mmol, as a mixture of regioisomers) in THF (4628 μl) at −78° C. was added methylmagnesium bromide (827 μl, 1.157 mmol, 1.4 M in toluene). The resulting solution was stirred at −78° C. for 1 h and warmed up to 0° C. for 30 min. 1N HCl was added to quench the reaction and the mixture was extracted with ethyl acetate (15 mL×2). ISCO purification (0-60% ethyl acetate in heptane) gave a mixture of the title compounds as a light yellow oil.

Step 4: 1-(5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-3-(hydroxymethyl)-6-(isopropylamino)pyrazin-2-yl)ethanol and 1-(6-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-3-(hydroxymethyl)-5-(isopropylamino)pyrazin-2-yl)ethanol

To a solution of 1-(3-(((tert-butyldimethylsilyl)oxy)methyl)-5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-6-(isopropylamino)pyrazin-2-yl)ethanol (137 mg, 0.255 mmol, as a mixture of regioisomers) in THF (2552 μl) was added TBAF (306 μl, 0.306 mmol) at RT. The reaction was stirred for 1 h then quenched with sat. NaHCO₃ (3 mL) and water (3 mL). The mixture was extracted with ethyl acetate (10 mL×2).

ISCO purification gave a mixture of the title compounds as a yellow oil.

Step 5: 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropyl-5-methylpyrazino[2,3-d]pyridazin-2-amine and 3-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-N-isopropyl-8-methylpyrazino[2,3-d]pyridazin-2-amine

A solution of 1-(5-(4-(2,4-difluorophenoxyl)piperidin-1-yl)-3-(hydroxymethyl)-6-(isopropylamino)pyrazin-2-yl)ethanol (31 mg, 0.073 mmol, as a mixture of regioisomers) and Dess-Martin Periodinane (78 mg, 0.183 mmol) in DCM (734 μl) was stirred at RT for 4 h. Then, 5-6 drops of NH₂NH₂—H₂O was added at 0° C. and the reaction mixture was stirred at RT for 1 h. HPLC purification gave the isolated title compounds. MS (ESI, pos. ion) m/z: 415.0 (M+1).

BIOLOGICAL EXAMPLES Example I Inhibition of cAMP Activity of GPR6 In Vitro Assay

This cell based assay measures the ability of compounds to inhibit the constitutive cAMP activity of GPR6 receptor expressed in CHO-K1 cells. CHO cells were stably expressed with GPR6 receptor, whose expression is controlled by a tetracycline inducable element. The cells were cultured in medium containing F12K, 10% FBS, 1% Penn/Strep, 200 ug/mL Hygromycin. GPR6 receptor expression was induced for 20 hrs with 1 μg/ml doxycycline (sigma D9891) in growth media. After addition of doxycycline cells were plated at a density of 250-500 cells per well in half-volume black clear bottom plates (Costar) and place in an incubator (37°, 5% C(O)2) for 20 hours prior to cAMP assays.

Culture media was removed from cells and they were washed with 50 μL of Ringer's Buffer (MgCl2 0.047 mg/mL, NaH2PO4 0.18 mg/mL, Na2HPO4 0.1 mg/mL, KCl 0.34 mg/mL, NaHC(O)3 1.26 mg/mL, D-glucose 1.8 mg/mL, NaCl 7 mg/mL; pH=7.4). Compounds suspended in DMSO were diluted in Ringer's Buffer containing 0.5% fatty acid free BSA and incubated on cells for 45 min at 37° and 5% C(O)2. After incubation cells were incubated for 10 min at room temp with Eu-cAMP tracer solution from a Perkin Elmer Lance HTRF UltracAMP assay kit (TRF0264). Then ULight™-anti-cAMP solution from the Lance HTRF kit was added and incubated on a shaker at room temp for 1 hour prior to HTRF detection in a BMG PolarStar Omega.

IC₅₀ curves were generated with a four-parameter logistic equation using GraphPad Prism 5.03. The specific compounds of this invention had an IC₅₀ value of less than about 100 micromolar.

In approximate IC₅₀ value of a representative number of compounds of Formula (I) in this assay is provided in the table below.

IC₅₀ IC₅₀ IC₅₀ IC₅₀ Cpd no. (um) Cpd no. (um) Cpd no. (um) Cpd no. (um) Compound Table 1 1 17.687 53 1.20 126 46.99 230 0.80 2 45.394 58 5.53 133 0.032 239 4.74 3 24.575 59 0.25 134 1.64 240 4.59 5 40.644 63 1.13 154 0.72 241 0.65 9 10.07 66 1.94 157 105.44 247 1.49 17 25.90 67 1.03 158 0.44 248 1.85 20 69.18 75 21.78 162 4.63 251 4.34 21 3.03 81 4.58 167 3.33 252 2.54 22 7.67 85 7.55 170 4.07 256 0.38 30 26.24 89 4.78 171 1.57 257 0.31 31 6.14 95 22.16 172 2.34 263 0.12 33 2.16 98 3.21 174 1.67 265 0.30 38 5.73 99 6.03 177 17.82 280 0.45 39 6.15 100 3.96 194 3.64 281 0.96 42 3.16 103 5.31 211 9.44 282 4.29 45 2.34 105 5.66 214 1.47 283 0.42 46 4.82 110 6.03 221 20.42 285 1.36 47 3.36 111 3.31 223 5.62 288 2.65 292 0.056 115 3.98 226 0.57 289 0.27 302 0.34 122 10.30 227 3.29 291 0.14 306 0.38 426 0.027 415 0.064 484 0.029 315 0.05 427 0.078 416 1.51 486 0.098 329 1.30 428 0.02 421 8.39 488 0.029 330 0.029 430 1.10 424 0.31 489 0.007 333 0.097 431 0.17 493 0.009 520 0.030 336 0.96 444 0.20 494 0.002 523 0.34 340 15.43 447 0.035 495 0.018 524 0.015 351 0.062 452 0.021 498 0.006 525 0.029 363 0.23 461 0.020 500 0.16 526 0.67 369 0.40 465 0.011 502 1.43 532 0.38 392 0.26 469 0.09 504 0.082 536 0.93 400 0.39 471 0.075 509 0.049 539 0.77 413 0.019 476 0.015 513 0.071 540 0.046 414 0.39 479 0.14 516 0.029 545 0.045 550 0.017 480 0.072 518 0.024 547 0.016 551 0.045 481 0.024 519 0.25 549 0.011 552 0.024 554 0.19 557 1.92 558 1.94 559 0.067 564 11 565 15.37 567 5.78 569 0.062 568 2.18 571 3.90 572 0.021 573 2.8 574 4.81 575 6.75 576 2.883 577 4.9 578 7.21 579 0.01 580 0.008 581 0.006 582 0.007 584 1.74 585 6.04 586 2.29 587 0.078 588 2.74 589 0.069 591 0.022 592 0.026 593 0.023 594 0.031 595 0.478 596 0.026 597 0.089 599 0.005 600 0.02 601 0.022 602 0.146 603 1.023 604 0.054 605 0.036 606 0.054 607 0.043 608 0.717 609 0.051 610 1.572 611 0.044 612 0.114 613 0.092 614 0.066 615 0.088 616 0.939 617 0.054 618 0.012 619 0.014 620 0.018 621 0.021 622 0.029 623 0.039 625 0.006 626 0.09 627 0.051 628 0.276 629 0.008 630 0.007 631 0.006 632 0.028 633 0.004 634 0.006 635 0.04 636 0.016 637 0.026 638 0.021 639 0.03 640 0.072 641 0.014 642 0.054 643 0.015 644 0.007 645 0.145 646 0.538 648 0.065 649 0.044 650 1.00 651 0.06 652 0.031 653 0.093 654 0.03 655 0.02 656 0.014 657 0.008 Compound Table 2 3 0.84 8 79.62 9 17.7 6 0.53 7 6.64

Example II Haloperidol-Induced Catalepsy In Vivo Rodent Parkinson's Disease Model

The motor symptoms of Parkinson's disease include akinesia, bradykinesia, rigidity, tremor and postural abnormalities and are associated with the loss of nigral dopaminergic cells and a decline in striatal dopamine levels. Administration of haloperidol to rodents leads to a transient parkinsonian-like state that is reversed by the administration of L-Dopa (Duty, S.; Jenner, P. Br. J. Pharmacol. (2011), 164, 1357-1391) and other drugs that have been clinically validated for the treatment of Parkinson's disease. Haloperidol antagonizes dopamine D2 and, to a lesser extent, D1 receptors in medium spiny neurons that comprise the indirect and direct pathways of the motor circuit respectively. The resultant block of striatal dopamine transmission results in abnormal downstream firing within the basal ganglia circuits that is manifest as symptoms of muscle rigidity and catalepsy. Catalepsy has been postulated to reflect the clinical features of Parkinson's disease, whereby patients experience an inability of to initiate movements.

Male Sprague-Dawley rats (Charles River, Calco, Italy) weighing 175-200 g are used. Alternatively, male C57B16 mice weighing 25-35 g were used. The cataleptic state was induced by the subcutaneous administration of the dopamine receptor antagonist haloperidol (0.3 mg/kg, sc), 90 min before testing the animals on the vertical grid test. For this test, the rats or mice were placed on the wire mesh cover of a 25 cm×43 cm plexiglass cage placed at an angle of about 70 degrees with the bench table. The subject was placed on the grid with all four legs abducted and extended (“frog posture”). The use of such an unnatural posture is essential for the specificity of this test for catalepsy. The time span from placement of the paws until the first complete removal of one paw (descent latency) was measured maximally for 120 sec for rats. For mice, the front paws of a mouse was placed on a horizontal metal bar raised 2″ above a Plexiglas platform and time was recorded for up to 30 seconds per trial. The test ended when the animal's front paws returned to the platform or after 30 seconds. The test was repeated three times and the average of the three trials was reported as the intensity index of catalepsy.

Catalepsy was measured 30 min, 120 min, and/or 240 min after dosing the subjects a 0.3 mg/kg i.p. dose of haloperidol along with the GPR6 modulator test compound. Test compound plasma and brain levels were determined by collected tissue samples at the end of the experiment, which was either at the 120 or 240 min time point. A representative number of compounds of the invention were administered in a dose range from 0.1 to 100 mg/kg i.p, sc or po in conjunction with haloperidol. The A2a antagonist KW6002 (istradefylline) was dosed at 0.6 mg/kg i.p. as a positive control. The compounds of the invention produced reversal of haloperidol-induced catalepsy. The results of a representative no. of compounds of this invention in this assay are disclosed in the table below.

Dose % reversal Cpd No. Species (mpk) Route 30 min 120 min 33 mouse 30 ip 48.1 41.4 53 ″ 30 ip 13.6 15.4 59 ″ 10 ip 42 18.8 59 ″ 30 ip 27.4 15.7 50 ″ 30 ip 40.4 29.6 415 rat 10 sc 36.9 25.1

FORMULATION EXAMPLES

The following are representative pharmaceutical formulations containing a compound of Formula (I).

Tablet Formulation

The following ingredients are mixed intimately and pressed into single scored tablets.

Quantity per tablet Ingredient mg compound of this invention 400 cornstarch 50 croscarmellose sodium 25 lactose 120 magnesium stearate 5

Capsule Formulation

The following ingredients are mixed intimately and loaded into a hard-shell gelatin capsule.

Quantity per capsule Ingredient mg compound of this invention 200 lactose spray dried 148 magnesium stearate 2

Injectable Formulation

Compound of the invention (e.g., compound 1) in 2% HPMC, 1% Tween 80 in DI water, pH 2.2 with MSA, q.s. to at least 20 mg/mL. 

What is claimed is:
 1. A compound of the formula:

wherein: R¹ is a heterocycloamino ring substituted with R^(a), R^(b), and R^(c) wherein: R^(a) is —Z—Ar where Z is C₁₋₆ alkylene, C₁₋₆ haloalkylene, —O—, —C(O)—, —NH—, or —S(O)n- wherein n is 0, 1, or 2; and Ar is C₃₋₁₀ cycloalkyl, C₃₋₇ heterocycloalkyl, C₃₋₇ heterocycloalkenyl, C₆₋₁₀ aryl, or C₁₋₉ heteroaryl wherein C₃₋₁₀ cycloalkyl, C₃₋₇ heterocycloalkenyl, C₃₋₇ heterocycloalkyl, C₆₋₁₀ aryl, and C₁₋₉ heteroaryl are optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, oxo, C₁₋₆ alkoxy, C₁₋₆ thioalkoxy, C₁₋₆ haloalkyl, C₁₋₆ hydroxyalkyl, C₁₋₆ haloalkoxy, C₁₋₆ alkylcarbonyl, C₁₋₆ alkylsulphonyl, cyano, C₂₋₁₂ alkoxyalkyloxy, C₁₋₉ amide, or C₁₋₆ hydroxyalkyloxy; and R^(b) and R^(c) are independently hydrogen, C₁₋₆ alkyl, hydroxy, or halo; R² is —OR^(e) or —NR^(d)R^(e) wherein R^(d) is hydrogen or C₁₋₆ alkyl and R^(e) is C₁₋₆ alkyl, C₁₋₆ haloalkyl, C₁₋₆ hydroxyalkyl, C₂₋₁₂ alkoxyalkyl, C₁₋₁₂ aminoalkyl, C₃₋₁₀ cycloalkyl, C₄₋₁₆ cycloalkylalkyl, C₆₋₁₀ aryl, C₁₋₉ heteroaryl, C₃₋₇ heterocyclyl, or C₃₋₇ heterocycloalkenyl wherein C₆₋₁₀ aryl, C₁₋₉ heteroaryl, C₃₋₇ heterocyclyl, and C₃₋₇ heterocycloalkenyl are optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, oxo, C₁₋₆ alkoxy, C₁₋₆ haloalkyl or C₁₋₆ haloalkoxy, or cyano; all X¹-X⁴ are carbon or one or two of X¹-X⁴ are N and the rest of X¹-X⁴ are carbon; R³, R⁴, R⁵, and R⁶ are independently absent, hydrogen, C₁₋₆ alkyl, halo, hydroxy, C₁₋₆ alkoxy, C₁₋₆ alkoxycarbonyl, C₁₋₆ haloalkyl, C₁₋₆ haloalkoxy, C₁₋₉ amide, C₃₋₇ heterocyclyl, C₁₋₈ alkylamino, or cyano; or a pharmaceutically acceptable salt thereof.
 2. The compound of claim 1 wherein R¹ is piperidinyl.
 3. The compound of claim 1 wherein R¹ is piperazinyl.
 4. The compound of claim 3 wherein Z is C₁₋₆ alkylene.
 5. The compound of claim 3 wherein Z is —C(O)—.
 6. The compound of claim 4 wherein Ar is C₆₋₁₀ aryl optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, oxo, C₁₋₆ alkoxy, C₁₋₆ haloalkyl, C₁₋₆ haloalkoxy, C₁₋₆ alkylcarbonyl, C₁₋₆ alkylsulphonyl, cyano, C₂₋₁₂ alkoxyalkyloxy, C₁₋₉ amide, or C₁₋₆ hydroxyalkyloxy.
 7. The compound of claim 4 wherein Ar is C₁₋₉ heteroaryl optionally substituted with 1 to 3 substituents independently selected from C₁₋₆ alkyl, halo, hydroxy, oxo, C₁₋₆ alkoxy, C₁₋₆ haloalkyl, C₁₋₆ haloalkoxy, C₁₋₆ alkylcarbonyl, C₁₋₆ alkylsulphonyl, cyano, C₂₋₁₂ alkoxyalkyloxy, C₁₋₉ amide, or C₁₋₆ hydroxyalkyloxy.
 8. The compound of claim 1 wherein R² is —NR^(d)R^(e) wherein R^(d) is hydrogen and R^(e) is C₁₋₆ alkyl or C₃₋₁₀ cycloalkyl.
 9. The compound of claim 1 wherein all X¹-X⁴ are carbon.
 10. The compound of claim 6 wherein all X¹-X⁴ are carbon.
 11. The compound of claim 1 wherein all X¹, X³, X⁴ are carbon, R⁶ is absent, and X² is N.
 12. The compound of claim 1 wherein all X¹, X², X⁴ are carbon, R⁶ is absent, and X³ is N.
 13. The compound of claim 1 wherein all X¹ and X⁴ are carbon, R⁵ and R⁶ are absent, and X² and X³ are N.
 14. The compound of claim 1, which is selected from the group consisting of: N-cyclopropyl-3-(4-(3-methylbenzyl)piperazin-1-yl)quinoxalin-2-amine; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(2,5-dichlorophenyl)methanone 2-(4-(3-chlorobenzyl)piperazin-1-yl)-N-phenylpyrido[2,3-b]pyrazin-3-amine; 3-(4-(4-bromobenzyl)piperazin-1-yl)-N-cyclopropylquinoxalin-2-amine; (4-(3-(cyclopropylamino)quinoxalin-2-yl)piperazin-1-yl)(3-isopropylphenyl)methanone; N-cyclopropyl-3-(4-(2,5-dichlorophenethyl)piperazin-1-yl)quinoxalin-2-amine; 3-(4-((2-chloro-5-(trifluoromethyl)phenyl)sulfonyl)piperazin-1-yl)-2-(cyclopropylamino)quinoxaline-6-carbonitrile; (4-chloro-2,6-difluorophenyl)(1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)methanone; (S)-2-(cyclopropylamino)-3-(4-((2,4-difluorophenyl)fluoromethyl)piperidin-1-yl)quinoxaline-6-carbonitrile; (1-(2-(cyclopropylamino)pyrido[3,4-b]pyrazin-3-yl)piperidin-4-yl)(pyrrolidin-1-yl)methanone; N-cyclobutyl-2-(4-(2,4-difluorophenoxy)piperidin-1-yl)pyrido[3,4-b]pyrazin-3-amine; and a pharmaceutically acceptable salt of any one of the above-mentioned compounds.
 15. The compound of claim 1, which is N-cyclopropyl-3-(4-(2,4-difluorobenzyl) piperidin-1-yl)-5-methylpyrido[3,4-b]pyrazin-2-amine or a pharmaceutically acceptable salt thereof.
 16. The compound of claim 1, which is (R)-N-cyclopropyl-3-(4-((2,4-difluorophenyl) fluoromethyl)piperidin-1-yl)-7-methylpyrido[3,4-b]pyrazin-2-amine or a pharmaceutically acceptable salt thereof.
 17. The compound of claim 1, which is 2-(cyclopropylamino)-3-(4-(2,4-difluorophenoxy) piperidin-1-yl)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide or a pharmaceutically acceptable salt thereof.
 18. The compound of claim 1, which is 3-(4-(2-fluoro-4-methoxyphenoxy) piperidin-1-yl)-N-i sopropylpyrazino[2,3-d[pyridazin-2-amine or a pharmaceutically acceptable salt thereof.
 19. The compound of claim 1, which is 3-(4-(4-chloro-2-fluorophenoxy) piperidin-1-yl)-2-(isopropylamino)-N,N-dimethylpyrido[3,4-b]pyrazine-7-carboxamide or a pharmaceutically acceptable salt thereof.
 20. The compound of claim 1, which is 3-(4-(2,4-difluorophenoxy)piperidin-1-yl)-N-isopropylpyrazino [2,3-d]pyridazin-2-amine or a pharmaceutically acceptable salt thereof.
 21. A pharmaceutical composition comprising a compound as defined in claim 1 or a pharmaceutically acceptable salt thereof and a pharmaceutically acceptable excipient. 